Book of Abstracts - uibk.ac.at · ported that "radiant matter" and gases have ... The contributions...

138
VIII IWEP & IW50YPPI 21/09 – 25/09/2009 Innsbruck, Austria 8 th International Workshop on Electric Probes in Magnetized Plasmas together with the International Workshop “50 Years Plasma Physics in Innsbruck” VIII IWEP & IW50YPPI VIII IWEP 2009 Innsbruck 8 th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck Edited by: Roman Schrittwieser, Codrina Ionita David Tskhakaya, Alexandra Avram http://www.uibk.ac.at/ionen-angewandte-physik/plasma/ Universitätsbuchhandlung & -verlag Book of Abstracts

Transcript of Book of Abstracts - uibk.ac.at · ported that "radiant matter" and gases have ... The contributions...

Page 1: Book of Abstracts - uibk.ac.at · ported that "radiant matter" and gases have ... The contributions to IWEP2009 in this Book of Abstracts have been ... Electron energy distribution

VIII IWEP

& IW50YPPI

21/09 – 25/09/2009

Innsbruck,

Austria

8th International Workshop

on Electric Probes in

Magnetized Plasmas

together with the

International Workshop

“50 Years Plasma Physics

in Innsbruck”

VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck

8th International Workshop on Electric Probes in Magnetized Plasmas

& International Workshop “50 Years Plasma Physics in Innsbruck”

21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Edited by: Roman Schrittwieser, Codrina Ionita David Tskhakaya, Alexandra Avram

http://www.uibk.ac.at/ionen-angewandte-physik/plasma/

Universitätsbuchhandlung & -verlag

Book of Abstracts

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Herausgeber: Roman Schrittwieser, Codrina Ionita-Schrittwieser, David Tskhakaya, Alexandra Avram

Book of Abstract

of the 8th International Workshop on Electric Probes in Magnetized Plasma

and of the International Workshop "50 Years Plasma Physics in Innsbruck"

September 21 to 25, Innsbruck, Austria

Studia Universitätsverlag 2009

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Alle Rechte, insbesondere das Recht der Vervielfältigung, der Verbreitung, der Speicherung in elektronischen Datenanlagen sowie der Übersetzung,

sind vorbehalten.

Copyright 2009 STUDIA Universitätsverlag,

Herzog-Sigmund-Ufer 15, A-6020 Innsbruck Umschlaggestaltung: R. Schrittwieser, C. Ionita-Schrittwieser, Alexandra Avram

Druck und Buchbinderei: STUDIA Universitätsbuchhandlung und –verlag,

Printed in Austria 2009 ISBN 978-3-902652-13-3

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VIII IWEP

& IW50YPPI 21/09 – 25/09/2009 Innsbruck, Austria

8th International Workshop on Electric Probes in Magnetized Plasmas together with the International Workshop “50 Years Plasma Physics in Innsbruck”

VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Book of Abstracts

Edited by: Roman Schrittwieser, Codrina Ionita, David Tskhakaya, Alexandra Avram

http://www.uibk.ac.at/ionen-angewandte-physik/

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International Scientific Committee

Michael Laux (Chairman) IPP Greifswald, Germany

John Allen University of Oxford, England, UK

Milan Čerček Jožef Stefan Institute, Ljubljana, Slovenia

Kyu Sun Chung Hanyang University, Seoul, Korea

Åshild Frederiksen University of Tromsø, Norway

Carlos Hidalgo CIEMAT Madrid, Spain

Mark Koepke West Virginia University, Morgantown, USA

Emilio Martines Consorzio RFX, Padova, Italy

Hans Werner Müller IPP Garching, Germany

Gheorghe Popa Alexandru Ioan Cuza University, Iaşi, Romania

Tsviatko Popov Sofia University St.Kliment Ohridski, Bulgaria

Jens Juul Rasmussen Risø - Danish Technical University, Denmark

Carlos Silva Instituto Superior Técnico, Lisbon, Portugal

Reiner Stenzel University of California, Los Angeles, USA

Jan Stöckel IPP Prague, Czech Republic

Local Organizing Committee

Roman Schrittwieser (Chairman)

Codrina Ionita-Schrittwieser

David Tskhakaya

Alexandra Avram (Workshop Secretary)

Franz Mehlmann

Christian Maszl

Johannes Grünwald

Patrick Hofreiter

E-mail: [email protected]

E-mail: [email protected]

E-mail: [email protected]

Phone: +43 512 507 6244

FAX: +43 512 507 2932

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List of contents

Acknowledgement .................................................................................... p. 6 8th International Workshop on Electric Probes in Magnet-ized Plasmas (IWEP2009) ........................................................................ p. 9 Foreword ................................................................................................... p. 9 Programme ............................................................................................. p. 10 Abstracts.................................................................................................. p. 15

International Workshop "50 Years Plasma Physics in Inns-bruck (IW50YPPI) ............................................................................... p. 103 Foreword ............................................................................................... p. 103 Programme ........................................................................................... p. 105 Abstracts................................................................................................ p. 107

List of participants (IWEP2009 & IW50YPPI) .................................... p. 128 Author Index (IWEP2009 & IW50YPPI) ............................................. p. 133

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Victor-Franz-Hess-Haus, Technikerstr. 25, as seen from South, The main entrance is above the ramp

Acknowledgement

The organizers of the 8th International Workshop on Electric Probes in Magnet-ized Plasma and of the International Workshop "50 Years Plasma Physics in Innsbruck", September 21 to 25, Innsbruck, Austria, would like to thank the University of Innsbruck for the permission to use the premises of the Victor-Franz-Hess-Haus and for the support of the workshops.

The support of our sponsors, Hiden Analytical and Pfeiffer Vacuum, is also gratefully acknowledged.

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8th International Workshop on Electric Probes in Magnetized Plasmas (IWEP2009),

September 21-23, 2009, Innsbruck, Austria

Foreword The biennial series of International Workshops on Electric Probes in Magnetized Plasmas

(IWEP) is devoted to understanding and solving problems associated with electric probes in either magnetized and unmagnetized plasmas. Probes are used to diagnose low-pressure discharge plasmas, space plasmas, edge-plasma regions of toroidal fusion experiments to atmospheric-pressure plasmas to name a few. As probes are material objects inserted into plasma, a comprehensive interpretation of probe measurements involves the local and nonlocal sheath physics. Even today, such interpretation over a wide range of plasma parameters is far from being fully complete. The contributions to the 8th International Workshop on Electric Probes in Magnetized Plasmas in Innsbruck will reflect the wide range of probe applications.

Rudimentary plasma probes were apparently used by Sir William Crooke in his experiments with the transport of electric current in thin gases. Crooke is commonly attributed to be the first scien-tist to comprehend the unique nature of ionized gases. But, well before Crooke, Michael Faraday re-ported that "radiant matter" and gases have significantly different properties. In modern plasma phys-ics, Irving Langmuir is the name that is inseparably connected to probe design and application because he is credited with the first comprehensive model and practical construction of plasma probes. Hence, we honour him with the terms Langmuir Probe and Langmuir Probe Theory.

Inaugurated by the Berlin Plasma Physics Group, the first International Workshops on Elec-tric Probes in Magnetized Plasmas were taking place in Berlin in 1993, 1995, 1997 and 2000. In 2003 the 5th IWEP took place in Greifswald, the 6th IWEP was organized in 2005 in Seoul, Korea, and the 7th IWEP in 2007 in Prague, Czech Republic, thus establishing an international reputation for IWEP.

The 8th IWEP is organized by the Innsbruck Experimental Plasma Physics Group at the Insti-tute for Ion Physics and Applied Physics at the University of Innsbruck. The meeting site is the Victor-Franz-Hess-Haus, named after Victor Franz Hess, who was in the 1930's Physics Professor at the Uni-versity of Innsbruck. He was the discoverer of the cosmic origin of the cosmic rays. During his profes-sorship in Innsbruck he founded an observatory for continuous registration of cosmic rays at the Hafe-lekar in an altitude of 2250 m, a mountain above Innsbruck, easily reachable by a cable car. In 1936 Victor Franz Hess was awarded the Nobel Prize in Physics for his discovery. The Hafelekar is worth a visit, non only because of the observatory but you will also have a marvellous view over Innsbruck and the surrounding mountains.

The contributions to IWEP2009 in this Book of Abstracts have been reviewed by the Inter-national Scientific Committee. The abstracts were not altered from the versions received, only copied into the Book of Abstracts. The sole responsibility for the content and style and possible typing errors rests with the authors. The authors are asked to prepare 6-page manuscripts according to the style re-quirements of Contribution to Plasma Physics and to deliver them in pdf-format to the organizers. Af-ter a reviewing process among the participants of IWEP2009 selected manuscripts will be published in a special issue of Contribution to Plasma Physics. Thus during and after the workshop, participants may be asked to take part in the reviewing process of the submitted manuscripts.

I would like to take this opportunity to thank all participants of the IWEP2009 for their at-tendance and contributions. International Scientific Committee, Innsbruck, September 2009

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Programme of the

8th International Workshop on Electric Probes in Magnetized Plasmas

Ground floor of Victor-Franz-Hess-Haus, Technikerstr. 25, Innsbruck, Auditorium (Hörsaal – HS) G and Foyer in front of it

Timing: 15 min presentation + 5 min discussion.

Sunday, September 20st

17:00 – 19:00 Registration

Monday, September 21st

08:00 – 08:45 Registration

08:45 – 09:00 Opening Ceremony

09:00 – 10:20 1. R. Stenzel, Time-dependent probe effects in magnetized plasmas p. 16 (topic 1)

2. A. K. Sarma, Measurement of plasma parameters in a positively biased plasma source p. 18 (topic 2)

3. S. Marsen, M. Otte, F. Steffen, and F. Wagner, Poloidal and toroidal asymmetries in turbulence activity in theWEGA stellarator p. 20 (topic 4)

4. R. Hatakeyama, Measurements of mode structure of shear-modified drift wave using Y- and Γ-shaped electro-static probes p. 22 (topic 4)

10:20 – 10:40 Coffee Break

10:40 – 12:00 1. M. Hannemann, New method for the determination of the electron temperature from Langmuir probe character-istics p. 24 (topic 9)

2. V. I. Demidov, Short dc discharge with wall probe as a gas analytical detector p. 26 (topic 9)

3. M. Komm, Particle-in-cell simulations of the ball-pen probe p. 28 (topic 9)

4. Tsv. K. Popov, Second derivative Langmuir probe di-agnostics of gas discharge plasma at intermediate pres-sures p. 30 (topic 9)

12:00 – 13:30 Lunch

13:30 – 14:00 Registration

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14:00 – 15:20 1. L. Conde, Measurements of plasma properties using fast

sweep Langmuir probes in unmagnetized weakly ionized plasmas p. 32 (topic 6)

2. J. M. Donoso, On the measurements of plasma properties using Langmuir probes for weakly ionized plasmas under drifting electrons populations p. 34 (topic 6)

3. V. A. Godyak, Electron energy distribution function in low pressure rf discharge p. 36 (topic 6)

4. N. Kurahara, Plasma energy spectrum measurement with two-stage parallel plate electrostatic analyzer for spacecraft charging potential determination p. 38 (topic 10)

15:20 – 15:40 Coffee Break

15:40 – 17:00 1. T. Suzuki, Thermal plasma effects on the impedance probe measurements in the ionosphere p. 40 (topic 10)

2. G. Zhong, Preliminary design on ITER divertor Lang-muir probes p. 42 (topic 11)

3. J. P. Gunn, Report on the physics and technical perform-ance of the Tore Supra tunnel probe p. 44 (topic 11)

4. G. De Masi, Flow measurements in the edge region of the RFX-mod experiment p. 46 (topic 11)

17:00 – 17:30 Registration

19:00 – 23:00 Informal welcome dinner (Griechische Taverne, Kranebitter Allee 144 – within walking distance from the meeting site!)

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Tuesday, September 22nd

08:30 - 10:10 1. F. Gennrich, Wavelet analysis of plasma edge turbulence probe measurements and simulations p. 48 (topic 11)

2. L. N. Mishra, Electron energy distribution in the Njørd rf plasma by means of an analogue differentiation method p. 50 (topic - other)

3. M. Y. Ye, Developments of divertor target-imbedded Langmuir probes for W7-X p. 52 (topic 5)

4. K. Todoroki, Influence of ion Larmor radius on radial profile of ion temperature measured by ion sensitive probe p. 54 (topic 3)

5. K. Uehara, Electrostatic probes for studying transport properties in tokamak plasmas p. 56 (topic 3)

10:10 – 10:30 Coffee Break

10:30 - 12:10 1. M. Kočan, Ion temperature measurements in the Tore Supra scrape-off layer using a retarding field analyzer p. 58 (topic 3)

2. W. Tierens, A novel cylindrical probe for measuring the ion temperature in magnetized plasmas p. 60 (topic 3)

3. Y. Tomita, Particle flux to spherical probe in weak mag-netic field p. 62 (topic 8)

4. H. W. Müller, Towards fast electron temperature meas-urements in the SOL of ASDEX Upgrade p. 64 (topic 11)

5. J. Adámek, Ball-pen probe measurements in L-mode and H-mode on ASDEX Upgrade p. 66 (topic 11)

12:10 – 13:40 Lunch

14:00 Departure Bus into town for Excursion (on Technikerstraße, near O-Bus station)

14:15 – 17:30 Excursion in town (after that bus will return to Technikerstraße)

18:30 Departure from Technikerstraße for guided walking tour (really very easy) to Kranebitter Klammstub'n

19:00 – 23:00 Banquet in Kranebitter Klammstub'n, Klammstraße 11

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Wednesday, September 23rd

08:40 - 10:20 1. R. W. Schrittwieser, A Probe Head for Simultaneous Measurements of Electrostatic and Magnetic Fluctuations in ASDEX Upgrade Edge Plasma p. 68 (topic 11)

2. I. S. Nedzelskiy, Mass-sensitive ion probe for edge plasma characterization on the tokamak ISTTOK p. 70 (topic 11)

3. M. A. Razzak, Probe diagnostics in microwave plasma jets at atmospheric pressure p. 72 (topic 12)

4. J. Kousal, Double probe measurements in magnetically enhanced RF plasma source at pressures below 0.1 Pa p. 74 (topic 12)

5. M. Tichý, Spatial distribution of plasma parameters in dc-energized hollow cathode plasma jet p. 76 (topic 12)

10:20 – 10:40 Coffee Break

10:40 – 12:00 1. P. Kudrna, A study of plasma parameters in hollow cathode plasma jet in pulse regime p. 78 (topic 12)

2. S. Saito, Development of asymmetric double probe for-mula and its application for collisional plasma p. 80 (topic 12)

3. J.-G. Bak, Electrical probe diagnostics for the KSTAR p. 82 (topic 11)

4. M. L. Solomon, Multi-channel analyzer investigations of ion flux at the target surface in Pilot-PSI p. 84 (topic 11)

12:00 – 13:30 Lunch

13:30 – 14:00 Session International Scientific Committee

14:00 – 15:20 1. N. Ezumi, Ion temperature measurements of the LHD stochastic magnetic boundary plasma using an ion sensi-tive probe p. 86 (topic 11)

2. S. K. Karkari, Application of floating hairpin probe in strongly magnetized plasma p. 88 (topic 11)

3. Tsv. K. Popov, Plasma potential and electron energy dis-tribution function measured by Langmuir probe in toka-mak edge plasma p. 90 (topic 11)

4. C. Ribeiro, A new look at fluctuation driven particle flux inferred by electrostatic triple probes p. 92 (topics 1, 2, 4, 7, 11)

15:20 – 15:40 Coffee Break

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15:40 – 17:00 1. C. Ionita, Emissive probes for the diagnostics of the

plasma potential in fusion experiments p. 94 (topic 11)

2. T. Gyergyek, Floating potentials in two-electron tem-perature plasma with two species of positive ions: theory and experiment p. 96 (topic 7)

3. D. Tskhakaya, Interpretation of Langmuir probe meas-urements during ELMs p. 98 (topic 7, 11)

4. S. Kuhn, Numerical matching of the sheath and plasma solutions for a spherical probe in low-density plasma p. 100 (topic 7)

17:00 – 17:30 Closing Ceremony

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Abstracts

of the 8th International Workshop on

Electric Probes in Magnetized Plasmas (IWEP2009)

September 21 – 23, 2009, Innsbruck University

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Time-dependent probe effects in magnetized plasmas

Reiner Stenzel and J. Manuel UrrutiaDepartment of Physics and Astronomy, University of California, Los Angeles, CA

90095-1547, USA

Workshop topic: 1. Mechanism of electron current saturationWe measured the time-dependent I-V characteristics of a plane probe with field-

aligned surface normal and probe dimension between electron and ion cyclotron radii.A rapid sweep of the probe voltage creates a current overshoot at the plasmapotential. A step function voltage above the plasma potential creates not only aninitial current overshoot but also recurring current spikes, i.e., a relaxation instability.The time-dependent I-V characteristics show no asymptotic shape or agreement withdc probe characteristics.

The cause of the instability has been identified: Electron collection by the positiveprobe raises the plasma potential in the flux tube of the electrode which expels theions across the field, depletes the density and creates a double layer at axial distanceslarge compared to the Debye length. The loss of plasma leads to a collapse of currentand potential profile, allowing the flux tube to partially refill until the process startsagain. The frequency of the relaxation process is determined by the electrode size andion sound speed. In addition, higher frequency microinstabilities are created in thecurrent channel where the electron drift approaches the electron thermal velocity.

The instability is due to the different dynamics of magnetized electrons andunmagnetized ions in EMHD plasmas. In a high electron-beta plasma the time-dependent probe current creates a significant magnetic perturbation, which propagatesin the whistler mode into the unperturbed plasma. Thus, a “simple” probe is no longera diagnostic device but a source of instabilities and waves.

References[1] J. M. Urrutia and R. L. Stenzel, Physics of Plasmas 4, 36-52 (1997)

Corresponding author addressReiner StenzelDepartment of Physics and Astronomy, University of California, Los Angeles, CA90095-1547, USAe-mail: [email protected]: 1 310 825 7898

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Measurement of Plasma Parameters in a Positively Biased Plasma Source

Arun Sarma, Ashish Patel and Supin Gopi

School of Petroleum Technology, Pandit Deendayal Petroleum University, Raisan, Gandhinagar 382007,

Gujarat, India. Workshop topic: 2, Accuracy in Electron Temperature Measurement The positive pulse bias (PPB) method has been proposed and developed for plasma-based ion implantation type of work. In this method, the plasma is biased to a positive high potential with respect to a target keeping at ground potential. It offers certain benefits as compared to other conventional negative biased plasma source. Characteristic features of the PPB method: Its arrangement, potential and current distributions and the necessary condition for the ion sheath formation are first discussed in contrast to the usual negative pulse bias (NPB) method. They include the floating potential measurement in the plasma and the energy analysis of the ions incident upon the target. Different probes viz., Plane and cylindrical Langmuir probe, Energy analyzer, different types of emissive probes (wire and laser heated) are being used to measure all plasma parameters in this source. Plasma characterizations at different plasma conditions useful for processing have also been carried out. All characterizations have been taken in both DC and RF plasma conditions. The sheath characteristics near the target are being measured extensively by the emissive probe. Finally spectroscopic diagnostics have been used to determine almost all parameters again and a comparative analysis of the measurements is made. It is confirmed that the ion energy agrees well with the potential energy across the sheath. Corresponding author address First Name and Surname: Arun Sarma Name of Institution: School of Petroleum Technology, Pandit Deendayal Petroleum University, Gandhinagar Street No., ZIP Town, Country: Raisan, Gandhinagar 382007, Gujarat, India. e-mail: [email protected] , phone: +91 79 23275005

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Poloidal and toroidal asymmetries in turbulence activity in the WEGA stellarator

S. Marsen, M. Otte, F. Steffen, and F. Wagner

Max-Planck-Institut für Plasmaphysik, EURATOM Association, D-17491 Greifswald, Germany

Workshop topic: 4, Multiple probe systems, probe arrays

The investigations of plasma turbulence requires a very high spatial (O(mm)) and tem-poral (O(s)) resolution. Both can be provided by Langmuir probes, as their resolution is in principle only limited by the probe or sheath dimensions and the sheath dynamics. In small devices with moderate plasma parameters, probe arrays are widely used to study the dynamics of turbulent structures and the underlying driving mechanisms. Several Langmuir probe sys-tems have been installed in the WEGA stellarator for turbulence studies. The most sophisti-cated system is a movable 2D matrix of 63 probes in the poloidal plane, which gives direct in-sight into the dynamics of turbulence perpendicular to the magnetic field. Previous experi-ments in WEGA indicated a poloidal asymmetry in the turbulence activity which could be verified by a comparison of fluctuations on the low and high field side of the torus. The pol-oidal one is linked to a toroidal asymmetry by the rotational transform. Therefore, the dynam-ics of turbulence parallel to the magnetic field was studied by measuring simultaneously at three different toroidal positions. It is compared to plasma flow measurements by Mach probes.

Corresponding author address: Stefan Marsen Max-Planck-Institut für Plasmaphysik, EURATOM Association Wendelsteinstraße 1, D-17491 Greifswald, Germany E-mail: [email protected], phone: +49 3834 882362

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Measurements of Mode Structure of Shear-Modified Drift Wave Using Y- and Γ-Shaped Electrostatic Probes

T. Kaneko and R. Hatakeyama

Department of Electronic Engineering, Tohoku University, Sendai 980-8579, Japan

Workshop topic: 4. Multiple probe systems, probe arrays

Flow velocity shears in magnetized plasmas have been recognized to strongly influence instabilities. Particularly in the field of space and fusion-oriented plasma physics, the velocity shear of magnetic-field aligned flows (parallel shear) is actively studied to understand physical properties of fluctuations occurring in the magnetized plasmas [1-3]. The purpose of this study is to investigate behavior of the collisionless drift wave instability experimentally in the presence of the parallel shear by measuring the mode structure such as axial and azimuthal wavenumbers, amplitude of the wave, and so on.

First, for identification of the azimuthal mode number m of the wave, we reconstruct an azimuthal wave structure as A(x, y) cos(δθ (x, y)), where A(x, y) is a wave amplitude profile in the plasma cross-section detected by a two-dimensional Γ-shaped probe, and δθ(x, y) is a wave phase difference between the Γ-shaped probe and a spatially-fixed reference probe. Using this probe system, the typical reconstructed azimuthal mode structure of the drift wave can be measured to be m=3. In the half plane, however, the wave amplitude appears to be strangely small, which is likely to result from an inevitable plasma-disturbance by the probe insertion into the plasma.

Next, for estimation of parallel wave number kz, a Y-shaped probe consisting of two Langmuir probes on the two tips with the separation d is adopted, enabling us to detect a relative wave phase difference δθ(φ) between the two tips, where φ is a probe-array/ magnetic-field orientation angle. Theoretically, the function of δθ(φ) represents a sinusoidal shape and then the value of δθ(0) will give kz for kz = δθ(0)/d in principle. However, phase difference signals around φ = 0 are observed to be suddenly irregular. A reduction in electron saturation current detected by one of the two probe tips, suggests that the irregularity is most likely due to a geometrical shielding of the plasma by the other probe tip. Hence, instead of direct detection of δθ(0), we evaluate the correct phase difference by interpolation with a curve fitted to the experimental data of δθ(φ) outside of the shielded φ range.

Based on these results, a simple dispersion relation in the local model has been calculated using the parameters of the measured wave mode structure and it can predict wave characteristics such as a growth rate similar to the experimental results. Our findings provide a potential for gaining a more profound insight into the physics of space/fusion plasmas. References [1] T. Kaneko, H. Tsunoyama, R. Hatakeyama, Phys. Rev. Lett. 90 (2003), 125001. [2] T. Kaneko, E.W. Reynolds, R. Hatakeyama, M.E. Koepke, Phys. Plasmas 12 (2005), 102106. [3] R. Ichiki, T. Kaneko, K. Hayashi, S. Tamura, R. Hatakeyama, Plasma Phys. Control. Fusion 51 (2009),

035011. Corresponding author address Rikizo Hatakeyama Department of Electronic Engineering, Tohoku University 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan e-mail: [email protected], phone: +81-22-795-7045

22

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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New Method for the Determination of the Electron Temperature from Langmuir Probe Characteristics

M. Hannemann

Plasma diagnostic group, Leibniz-Institute for Plasma Science and Technology Greifswald e.V., Felix-Hausdorff-Strasse 2, 17489 Greifswald, Germany

Workshop topic: 9, advanced and innovative probe concepts

The electron retarding current collected by a Langmuir probe in a plasma possessing a Maxwellian electron energy distribution function at potentials V lower than plasma potential is a an exponential function: ie,ret (V) ∝ exp(V/Ve). Ve is the electron temperature Te in voltage units: Ve = kTe /e0 (k: Boltzmann constant, e0: elementary charge). Usually, Ve is derived from the slope of ln ie,ret (V). Another possibility is the method of the floating ac probe. Here the probe current is modulated superposing a small sinusoidal voltage v(t) = v0 cos ωt on the steady probe bias. The temporal mean of the modulated exponential electron retarding current than is given by <ie,ret (V(t))> = I0(v0/Ve) ie,ret (V) with I0 as zeroth order modified Bessel function [1]. This leads to a shift ΔVf = Ve ln I0(v0/Ve) between the floating potentials of modulated and unmodulated probe current from which Ve may be obtained [2], [3]. A similar principle for Ve determination is adopted in [4]. Here the shift of the floating potential of a heated and unheated emissive probe is used.

The principle of the methods described above is based on the fact that an exponential probe current subjected to an electrical averaging process differs from the unaffected current only by a factor independent on the probe potential. Such an averaging may be performed also by smoothing of the characteristic by means of non-recursive digital filters, also called finite impulse response filters, after measurement. It is shown, that also a smoothed exponential probe current differs from the unsmoothed one by a factor independent on probe potential. Therefore, the electron temperature may be obtained from the shift of the floating potential of smoothed and unsmoothed characteristic but also directly from the enlargement of the electron retarding current by smoothing. This new method combines all advantages of the electrical methods, but it is free of their disadvantages. A suitable smoothing filter is chosen and all means necessary for the practical realization of the method are given. The influence of the ion current on the determined value of Ve is investigated. The convenience of the method is shown by means of testing calculations and a measuring example.

References [1] A. Boschi, F. Magistrelli, Il Nuovo Cimento 29, (1963), 487 [2] S. Aihara, G. Lampis, Lettre Al Nuovo Cimento 2, (1971), 1309 [3] Earl R. Mosburg, Jr., Rev. Sci Instrum. 52, (1981), 1182 [4] H. Shindo, M. Konishi, T. Tamaru, Rev. Sci. Instrum. 59, (1988), 2002

Corresponding author address

Mario Hannemann Leibniz-Institute for Plasma Science and Technology Greifswald e.V. Felix-Hausdorff-Strasse 2, 17489 Greifswald, Germany e-mail: [email protected], phone: +49 3834 554 425

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Short DC Discharge with Wall Probe as a Gas Analytical Detector

V. I. Demidov1, S. F. Adams

2, J. Blessington

1, M. E. Koepke

1, J. M. Williamson

3

1Department of Physics, West Virginia University, Morgantown, WV 26506, USA

2Air Force Research Laboratory, WPAFB, OH 45433, USA

3ISSI, 2766 Indian Ripple Rd., Beavercreek, OH 45440, USA

Workshop topic: 9, advanced and innovative probe concepts

A method to measure fine structures, associated with atomic and molecular plasma

processes, in the energetic part of the electron energy distribution function (EEDF) in afterglow

plasmas is known as plasma electron spectroscopy (PLES) [1]. It has been suggested that PLES

can be used for the determination and control of absolute densities of the gas mixture

components [2]. A new approach, leading to the development of a gas analytical detector, based

on PLES measurements in the near-cathode plasma is reported here. A short DC discharge with

conducting walls and cold cathode was used to measure the EEDF during the discharge instead

of the afterglow. EEDF measurements during the discharge are technically simpler and have

dramatically better sensitivity than in the afterglow since temporal resolution is not required.

Instead of the more common cylindrical Langmuir probe, the conducting wall is used as the

electric probe resulting in a dramatic increase in probe sensitivity. The wall probe being almost

flat also greatly reduces the ion current contribution to the measurements.

Utilization of the wall as an electric probe for the measurements is possible under the

condition of nonlocality of the EEDF [3]. The condition of nonlocality is related to the

dimension of the plasma volume and the gas pressure. For example, in noble gases for the

elastic electron collisions, the condition is typically p×R < 10 Torr×cm, where p is the gas

pressure and R is the volume radial dimension. Thus at atmospheric pressure, the discharge

dimension can be as small as 0.1 mm and satisfy the electron nonlocality condition. This in turn

allows the possibility of developing a micro-analytical gas sensor (PLES detectors) operational

up to atmospheric pressure.

This work was supported by the Air Force Office of Scientific Research.

References [1] V. I. Demidov, N. B. Kolokolov, Sov. Phys. J. 30 (1987) 97.

[2] V. I. Demidov, C. A. DeJoseph, Jr., Rev. Sci. Instrum. 77 (2006) 116104.

[3] L. D. Tsendin, Plasma Source Sci. Technol. 4 (1995) 200.

Corresponding author address

Vladimir Demidov

West Virginia University

Hodges Hall, Morgantown, WV 26506-6315, USA

e-mail: [email protected], phone: +1 937 255 6794

26

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Particle-In-Cell simulations of the Ball-pen probe

M.Komm1,3, J.Adamek2, Z. Pekarek3, R. Panek2

1Ghent University, Ghent, Belgium;2Institute of Plasma Physics ASCR, v.v.i., Association EURATOM/IPP.CR, Prague, Czech Republic;

3Charles University, Prague, Czech Republic

Workshop topic: 9, Advanced and innovative probe concepts

The Ball-pen probe (BPP) is an advanced probe designed for direct measurements of plasma potential in the SOL of tokamaks. It has been developed during recent years at Institute of Plasma Physics ASCR (IPP) in Prague and used in experiments [1,2]. The experimental results indicate, that BPP follows the basic idea that the floating potential Vfl of its collector is equal to the plasma potential

V pl, when the ratio of the electron and ion saturation currents are balanced, in agreement with the standard Langmuir probe theory. However, the behavior of the probe has not yet been completely understood.

In order to verify standard theory of Langmuir probe in the case of BPP with complex geometry, a number of Particle-In-Cell simulations have been performed. We have studied scenarios, where the probe collector is partially exposed to the plasma to minimize the influence of the surface effects and plasma turbulence. In this case, the direct flux of ions and electrons to the probe collector can be modeled by means of kinetic simulations. The simulations were performed by using 2D Particle-in-Cell Cartesian code Spice [3], which has been previously benchmarked with experiment [4]. The code has been adapted to provide fast simulations of electrodes at the floating potential.

The goal of the simulations is to obtain the dependence of the ratio of the electron and ion saturation currents on the floating potential of the ball-pen probe collector with respect to its position and hence verify whether this potential is equal to the plasma potential for the case of balanced saturation currents.

[1] J. Adámek, J. Stöckel, M. Hron, J. Ryszawy, M. Tichý, R. Schrittwieser, C. Ionita, P. Balan, E. Martines, G. Van Oost,

Czechoslovak J. Phys. 54 (2004) C95-C99.

[2] J. Adamek, V. Rohde, H.W. Müller, A. Herrmann, C. Ionita, R. Schrittwieser, F. Mehlmann, J. Stöckel, J. Horacek, J.

Brotankova, Journal of Nuclear Materials 390-391 (2009) 1114-1117.

[3] R. Dejarnac, M. Komm, J.P. Gunn, R. Panek, Journal of Nuclear Materials, 818-821 (2009),390-391

[4] R. Dejarnac, M. Komm, J. Stöckel, R. Panek, Journal of Nuclear Materials, 31-34 (2008), 382

Corresponding author address

Michael KommInstitute of Plasma Physics ASCR, v.v.iZa Slovankou 3Praha 8180 00Czech [email protected], +420 777 553 579

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Second Derivative Langmuir Probe Diagnostics of Gas Discharge Plasma at Intermediate Pressures

Tsv. K. Popov1, M. Dimitrova2

1 Faculty of Physics, St. Kl. Ohridski University of Sofia,5 J. Bourchier Blvd., 1164 Sofia, Bulgaria

2Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria

Workshop topic: 9. Advanced and innovative probe concepts

The literature on Langmuir probe measurements contains thousands of references.

Among the contact methods of plasma diagnostics, the electric probes are the least expensive

and are still the fastest and most reliable diagnostic tools allowing one to obtain the values of

very important plasma parameters - Langmuir probes are known for their ability to provide

local measurements of the plasma potential, the density and the energy distribution functions

(EDF) of charged particles.

The probe technique is relatively simple when all the requirements of the “classical”

theory are satisfied. Probes usually operate at gas pressures in the range of 0.1 Pa to 100 Pa.

In many different contemporary technologies, such as plasma chemistry, etching, plasma

polymerisation, thin layer dielectric deposition, etc., a relatively high gas pressure of 100 –

1000 Pa is required. In this case the theoretical interpretation of the experimental data

acquired becomes more complicated.

This work is a review of the contributions advancing the use of probes at extended gas

pressures. We present an overview of the deviations from the “ideal” conditions for probe

measurements the latest solutions that we have been using to overcome such problems. The

main task of our considerations is how to determine the actual plasma characteristics from the

data measured by a Langmuir probe, especially in what concerns the plasma potential, the

density and the electron energy distribution function (EEDF) at intermediate gas pressures of

100 – 1000 Pa. In this respect, we describe a refinement of the second derivative technique

that takes into account the charged particles depletion caused by their sinking on the probe

surface, and we discuss how the results can be processed in order to retrieve the correct values

of the plasma parameters under these extended pressure conditions.

Corresponding author address Tsviatko Popov Faculty of Physics at St Kliment Ohridski University of Sofia 5, James Bourchier Blvd, 1164 Sofia, BULAGARIA [email protected] Cell phone +359 888 33 91 21 Phone +359 2 81 61 738

30

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

31

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Measurements of plasma properties using fast sweep Langmuir probes in unmagnetized weakly ionized plasmas

L. Conde 1 , E. Criado1, J.M. Donoso1,G. Herdrich2 and O. Troll1

(1) Departamento de Física Aplicada, E.T.S. Ingenieros Aeronáuticos.Universidad Politécnica de Madrid 28040 Madrid, Spain.

(2) Institut für Raumfahrtsysteme (IRS). Universität Stuttgart. Pfaffenwaldring 31, D-70550. Stuttgart. Germany.

Workshop topic: 6, Detection and consequences of non-thermal distributions.

The design and performances and of a simple circuit for fast sweep measurements using either, collecting and emissive Langmuir probes are discussed [1]. The experimental results obtained under ideal conditions with Maxwellian plasmas in electric discharges are presented and compared with those obtained with similar devices [2-4]. The experiments indicate that the effective upper bound for the maximum frequency sweep, using collecting probes in weakly ionized plasmas, is not caused by the limitations of the electrical circuitry. On the contrary, the pulse repetition time limit is originated by the speed acquired by the ions in a collisional mean free path. This fast sweep systems bias the probe by means of a time dependent voltage ramp and the massive ions are accelerated towards the probe for negative bias voltages would not follow the fast change of the probe electric field. In consequence, the drained probe current below the plasma potential, which is composed of attracted ions and repelled electrons, becomes affected by the slow response of ions to fast voltage ramps. The formation of the plasma sheath around the probe and consequently, the orbital motion of attracted ions is hindered by the fast change in the electric field around the probe. This inertial effect of heavy particles would be enhanced by the collisions of ions with neutrals which results in the local confinement of the massive particles. This collisional time-dependent response of collecting Langmuir probes is evidenced in the current voltage curves which are compared for different characteristic sweep times. The effect introduced by the neutral gas pressure in this collisional time-dependent response will be also discussed.

References

[1] E. V. Shun'ko, Langmuir Probe In Theory And Practice, Universal-Publishers (2009)[2] S.P. Gerhardt et al. Rev. Sci. Instrum. 75, (2004) 4621 [3] L. Giannone et al. Phys. Pasmas. 1 (1994), 3614[4] G. Delle Cave and G. Fabricatore. IEEE Trans. Plasma Sci. 19 (1991), 651

Corresponding author address

Dr. Luis Conde Dpto. Física Aplicada, ETS Ingenieros Aeronaúticos. Universidad Politécnica MadridPlaza Cardenal Cisneros 3, 28040 Madrid, Spain.E-mail: [email protected], phone: +34 913366305.

32

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

33

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On the measurements of plasma properties using Langmuir probes for weakly ionized plasmas under drifting electrons populations.

J.M. Donoso and L. Conde

Departamento de Física Aplicada, E.T.S. Ingenieros Aeronáuticos.Universidad Politécnica de Madrid 28040 Madrid, Spain.

Workshop topic: 6, Detection and consequences of non-thermal distributions.

In some current carrying laboratory plasmas it is often found the presence of drifting or different coexisting electron populations. This situation is usually described by using superimposed electron drifting Maxwellian distributions which complicates the classical analysis for repelled electrons of the current voltage characteristic curves of collecting Langmuir probes [1,2]. These models could explain some deviations measured in the electron current. However, the drifting Maxwellian models rely on the implicit assumption of a collisional regime for all electron populations neglecting the possibility of other kind of electron distributions which could be more accurate in certain contexts. The calculation of the collected current for repelled electrons by cylindrical Langmuir probes is reviewed. For drifting electrons incoming in the perpendicular direction to the probe not only drifting Maxwellians can be used but also some more general recently described distribution functions in a power-low form [3] are examined. The theoretical results are compared with actual experimental measurements obtained in plasma double layers.

References

[1] A. H. Heatley, Phys. Rev. 52 (1937), 235[2] E. V. Shun'ko, Langmuir Probe In Theory And Practice, Universal-Publishers (2009).[3] R. P. Singhal_ and A. K. Tripathi, Phys. Plasmas, 13 (2006), 012102

Corresponding author address

Dr. J.M. Donoso.Dpto. Física Aplicada, ETS Ingenieros Aeronaúticos. Universidad Politécnica MadridPlaza Cardenal Cisneros 3, 28040 Madrid, Spain.E-mail: [email protected], phone: +34 913366305.

34

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

35

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Electron Energy Distribution Function in Low Pressure RF Discharges

V. A. Godyak RF Plasma Consulting, 1265 Beacon Street, # 402, Brookline, MA 02446, USA

Detection and consequences of non-thermal distributions

Weakly ionized gas discharge plasmas are characterized with variety of nonequilibrium

conditions. In such plasmas, electrons are not in equilibrium with ions and neutrals and

they are not in equilibrium within their own ensemble, resulting in a significant departure

of the electron energy distribution function (EEDF) from the equilibrium Maxwellian

distribution. In low pressure rf discharges sustained by nonuniform electromagnetic field,

non-Maxwellian EEDF and their scalar integrals (Te, ne and rates of collisional processes)

are not in a local equilibrium with the electromagnetic field. Moreover, this nonlocal

electron heating and nonlocal electron kinetics are frequently governed by collisionless

interaction of electromagnetic field with warm electrons at the condition of nonlocal

plasma electrodynamics when plasma current is a no local function of the

electromagnetic field. Principle, measuring technique, apparatus and processing of the

probe characteristic for EEDF measuring in gas discharge plasmas are discussed in this

presentation together with examples of EEDF obtained in low pressure rf capacitive and

inductive discharges. Formation of nonequilibrium EEDFs at condition of nonlocal

electron kinetics and nonlocal plasma electrodynamics in low pressure rf discharges is

discussed on the examples of measured and calculated EEDFs.

Valery Godyak

RF Plasma Consulting

1265 Beacon Street, # 402,

Brookline, MA 02446, USA

[email protected] 001-617-738-7263

36

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

37

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Plasma Energy Spectrum Measurement with Two-Stage Parallel Plate

Electrostatic Analyzer for Spacecraft Charging Potential Determination

N. Kurahara and M. Cho

Department of electric engineering, Kyushu Institute of Technology, 1-1 Sensui, 804-8550, Kitakyushu, Japan

Workshop topic: 10. Probes in space and propulsion systems

Plasma parameters and charging potential, which are equal to plasma potential, are

needed for safe spacecraft operations [1], as well as for the development of new materials or

simulation tools for use in space. The in-orbit measurements of the plasma environment and

spacecraft charging have been performed over the past five decades, but the results have

often required multiple large instruments to attain good accuracy. Charging measurement

devices do not provide wide coverage measurement ranges, because it is difficult to measure

low-potentials (1V-100V) and high-potentials (100V-20kV) with good accuracy using a

single device [2]. Langmuir probes

[3] were often used for low-potential measurements. This

method is easy, but requires high bias voltages to measure high potentials. On the other hand,

electrostatic analyzers [4] were used for the high-potential measurements. These devices can

measure high potentials with low bias voltages, but the mechanics and the electrical circuits

are complex.

In order to obtain a wide measurement range (1V-20kV) with good accuracy and with

using only one device, a new type of electrostatic analyzer using two-stage parallel electrodes

is being developed. The analyzing electrode contains two stages of parallel plates. Each stage

has the same distance between electrodes and is on the same vertical axis. One of the two

electrodes is biased while the other is connected to the ground (GND) of the analyzer, which

is equal to spacecraft potential. This device measures the plasma energy spectrum, the

spacecraft charging potential is determined by analyzing the energy spectrum change. The

experimental model was tested in a chamber filled with Xenon plasma, and the charging

potential was varied between -10V and -500V. The results obtained determined the energy

spectrum change needed to characterize the behavior of the proposed device. The obtained

results show the required bias voltage of the measurement is one-tenth of the charging

potential, which is very promising.

References [1] H. C. Koons, J. E. Mazur, R. S. Selenick, J. B. Blake, J. F. Fennell, J. L. Roeder, and P. C. Anderson, The

impact of the space environment of space systems. Proceedings of: the 6th Spacecraft Charging Technology

Conference (6 November 1998, Massachusetts, U.S.A).

[2] H. B. Garrett, The charging of spacecraft surfaces. Contrib. Reviews of Geophysics and Space Physics 19

(1981), 4.

[3] I. Langmuir, and K. B. Blodgett, Currents limited by space charge between concentric spheres. Contrib.

Phys. Rev. 24 (1924), 49.

[4] F. R. Paolini, and G. C. Theodoridis, Charged particle transmission through spherical plate electrostatic

analyzers. Contrib. The review of scientific instruments 38 (1967), 5.

Corresponding author address

Naomi Kurahara

Kyushu Institute of Technology

1-1 Sensui, Tobata-ku, 804-8550 Kitakyushu, Japan

e-mail: [email protected]

phone: +81-93-884-3229

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

39

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Thermal plasma effects on the impedance probe measurements in the

ionosphere

T. Suzuki1, T. Ono1, J. Uemoto2, A. Kumamoto1, T. Abe3

1Graduate School of Science, Tohoku University, 980-8578 Sendai, Japan

2National Institute of Information and Communications Technology, 184-8795 Tokyo, Japan 3Institute of Space and Astronautical Science, 229-8510, Sagamihara, Kanagawa, Japan

Workshop topic: 10, Probes in space and propulsion systems

Impedance probe has been developed as a powerful tool to measure absolute values of the electron number density [1]. The impedance probe has been installed on many sounding rockets and spacecrafts for electron density measurements in space plasmas. It has been recognized that the probe impedance reflects various physical quantities of plasmas as well as the electron density. In order to evaluate the finite temperature effects on the impedance probe measurements, we examine the probe impedance obtained from the sounding rocket experiment conducted in the ionosphere.

The active experiment releasing Lithium in the ionosphere has been conducted by the sounding rocket S-520-23, which was launched from Uchinoura Space Center, Japan on 2nd September, 2007. We analyze the sheath capacitance measured from the impedance probe onboard the sounding rocket. Equivalent probe capacitance observed at enough lower frequency than the sheath resonance frequency corresponds to the sheath capacitance. We find that measured sheath capacitances agree well with the calculations based on the study of Oya and Aso [2]. It means that the Debye length can be estimated from impedance probe measurements. We apply this technique to deduce the electron density after Li releases from the rocket. Sheath capacitances indicate the sharp enhancement of the electron density about 1-2 order of magnitude after the each Li release.

We also study the Q value of the upper hybrid resonance. The Q values show clear dependence on the Debye length. The kinetic effect of plasmas should affect the impedance probe measurements. References [1] H. Oya, T. Obayashi, Rep. Ionos. Space Res. Japan 20 (1966), 199. [2] H .Oya, T. Aso, Space Research IX (1969), 287. Corresponding author address Tomonori Suzuki Graduate School of Science, Tohoku University 6-3 Aramaki-Aza-Aoba, Aoba-ku, 980-8578 Sendai, Japan e-mail: [email protected], phone: +81-22-795-6518

40

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

41

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Preliminary design on ITER divertor Langmuir Probes

G. Zhong1, C. S. Pitcher2, P. Andrew2, Y. Tang1, G. Jian1, Q. Yang1

1 Center for Fusion Science, Southwestern Institute of Physics, 3, 3rd Section, South of 2nd Ring Road, 610041, Chengdu, P. R. China

2ITER Diagnostic Division, ITER Cadarache Joint Work Site, 13108, St. Paul-Les-Durance, Cedex, France

Workshop topic: 11, Probe applications in fusion-oriented devices

ITER divertor Langmuir Probes will be installed on 5 of the 54 ITER divertor cassettes to measure the divertor plasmas and monitor a number of plasma processes such as detachment/attachment status, position of strike points, and ELMs bursts on the divertors. Design of the ITER Langmuir probes is ongoing within the Chinese Domestic Agency and ITER International Organization and the R&D activities are being conducted in China. The ITER Langmuir probe diagnostic is characterized by a large number of probes, high and quasi-stationary heat loads, operation lifetime, and predefined installation geometry.

For each of the five divertor cassettes, an array of about 80 probes will be attached poloidally along the cassette’s edge with the majority of probes on the outer and inner vertical targets, emphasizing monitoring of plasmas on the vertical targets. To allow the ITER Langmuir probe diagnostic to monitor plasma behavior as well as basic plasma parameters, a switching between different modes of operation is foreseen: swept single probes, biased single probes, and triple probes. The probe temperature is one of the top concerns in the design, on which probe erosion and interpretation of diagnostic data are highly dependent. Probes near the strike points will be subject to normal heat flux of 10 MW/m-2 and transient heat flux of 20 MW/m-2 with a duration of 10 seconds. The heat flux on the probes is mainly removed by thermal conductance from the probes to the divertor tiles, which act as the heat sinks for the probes. For a given heat load the temperature of the probe tips is determined mainly by the thermal resistance of the probe body. Therefore the probe structure and materials used should be optimized. A staircase-like probe structure will be discussed for the purpose of reducing the temperature of the probe tip and for an indicator of erosion level of the adjacent divertor tile.

Corresponding author address Guangwu Zhong Southwestern Institute of Physics 3, 3rd Section, South of 2nd Ring Road, 610041, Chengdu, P. R. China e-mail: [email protected], phone : +86 28 82850314

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Report on the physics and technical performance of the Tore Supra tunnel probeJ. P. Gunn, M. Kočan

CEA, IRFM, F-13108 Saint Paul Lez Durance, France.

Workshop topic : 11. Probe applications in fusion-oriented devicesMany novel Langmuir probe designs have been proposed over the years to measure

strongly magnetized plasmas. Often their correct calibration is difficult or impossible due to the 3D nature of the problem. It is the lingering doubt about their validity that prevents wide spread implementation of a number of such probes in tokamaks. We took the approach of designing a probe with imposed symmetry, guided by what we thought we were capable of simulating with a 2D particle-in-cell code. The result is a new kind of Langmuir probe called the "tunnel probe" for use in the tokamak scrape-off layer [1]. It consists of a hollow conducting cylinder, the "tunnel", with both depth and diameter of typically a few millimetres. It is closed at one end by an electrically insulated "back-plate". The conductors are mounted in an insulating body. The tunnel axis is parallel to the magnetic field. Plasma flows into the open orifice and the ion flux is distributed between the tunnel and the back plate. The kinetic simulations of the probe showed that the radial electric field of the magnetized sheath deflects a portion of the incident ions away from their guiding center trajectories onto the tunnel. The ratio of current collected by the tunnel to that of the back-plate is a function of the local plasma parameters, especially ion current density and electron temperature Te. In principle then, dc measurements of this ratio can provide fast, simultaneous measurements of those two quantities.

Perhaps the most interesting and pragmatic result of the kinetic simulations is that despite the strong influence of the sheath electric field on the distribution of ion flux inside the tunnel, it does not penetrate into the plasma. The ion trajectories leading up to the mouth of the tunnel are totally unperturbed. That is, the effective ion collecting area of a concave Langmuir probe is exactly equal to the geometrical cross section of its orifice projected along the field lines, which means that such a probe would be absolutely calibrated for the measurement of parallel ion current density, if secondary electron emission is taken into account. This characteristic provides a significant advantage over standard convex probes whose effective collecting areas are larger than their geometrical cross sections due to focusing of ions onto the surface by the sheath electric field that expands outward into the plasma. Dedicated experiments to reconstruct the line-averaged density measured by a nearby interferometer cord gave nearly perfect agreement.

After five years of intensive operation in Tore Supra (deuterium or helium plasma, B=2-4 T), we report on the physics and technical performance of the tunnel probe. Until now the probe has made 3113 reciprocations up to and even inside the LCFS of nearly every discharge scenario, with additional heating up to 12 MW. Real time feedback control of the applied bias voltages optimizes the dynamic range of the measurement. The huge range of SOL plasma parameters obtained in Tore Supra allows us to make detailed comparisons between measurements, physics-based scalings, and kinetic simulations.[1] J. P. Gunn, Phys. Plasmas 8, 1040 (2001); J. P. Gunn, et al., Czech. J. Phys. 55, 255 (2005).

Corresponding author addressJames P. Gunn

Institut de recherches sur la fusion magnétique, CEA Cadarache

F-13108 Saint-Paul-lez-Durance, France

e-mail: [email protected], phone: +33 442 257 902

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Flow measurements in the edge region of the RFX-mod experiment

G. De Masi, M. Spolaore, R. Cavazzana, P. Innocente, R. Lorenzini, E. Martines, B. Momo,

S. Munaretto, G. Serianni, S. Spagnolo, D. Terranova, N. Vianello, M. Zuin

Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, corso Stati Uniti 4, 35127, Padova, Italy

Workshop topic: 11. Probe applications in fusion-oriented devices

Plasma flow measurements in the edge region of fusion devices is a very important

task, given the strong impact of these flows on turbulence correlation properties and on the

associated transport. In this contribution a detailed study of the edge flow properties

performed in the outer region of the RFX-mod reversed field pinch experiment using a

Gundestrup probe is presented. In particular, both parallel and perpendicular components

(with respect to the magnetic field) have been evaluated in several low current discharges

providing a complete reconstruction of the edge flow profiles.

Different methods based on both magnetized and unmagnetized models have been used

to evaluate the averaged plasma flow components and their time variations. Furthermore,

configurations involving either ion saturation current signals or floating potential ones have

been compared to evaluate both parallel and perpendicular flow components and a good

agreement has been found between different methods. In the two cases, the dynamic behavior

of edge flow fluctuations induced by dynamo relaxation events peculiar of RFP

configurations and by gradient modifications following pellet injection have been studied.

Corresponding author address Gianluca De Masi

Consorzio RFX

corso Stati Uniti 4, 35127 Padova, Italy

email: [email protected]

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Wavelet analysis of plasma edge turbulence probe measurements and simulations

F. Gennrich, J. Peer, A. Kendl, F. Mehlmann, R. Schrittwieser

Institute for Ion Physics and Applied Physics, Association Euratom-ÖAW, University of Innsbruck, Austria

Workshop topic: 11. Probe applications in fusion oriented devices

Instabilities and turbulence are of high interest in fusion physics, and a detailed understanding is essential for a successful operation of upcoming fusion experiments. Two dimensional turbulent mixing leads to particle and energy transport perpendicular to the magnetic field, and especially the outer parts of a tokamak are subject to various instabilities such as Edge Localised Modes (ELMs).

In order to reveal potential similarities or special features, both classical analysis methods and Wavelet methods have been applied on Langmuir probe measurements of Type I ELMs obtained at ASDEX Upgrade [1,2]. Moreover, simulation data produced with a gyrofluid code have been investigated for comparison.

Wavelet techniques allow a deeper insight into the characteristics of fluctuation data by means of a time-scale representation. Consequently, they provide a reasonable addition to common statistical tools like probability density and correlation functions or Fourier spectrograms, particularly for data in the case of highly non stationary events like ELMs.

References:

[1] F. Mehlmann, C. Ionita, H.W. Müller, P. Balan, A. Herrmann, A. Kendl, M. Maraschek, V. Naulin, A.H. Nielsen, J.J. Rasmussen, V. Rohde, R. Schrittwieser and the AUG Team. Radial transport in the L- and H-mode SOL of ASDEX Upgrade. 13th EU-US TTF Workshop (1.-4.9.2008, Copenhagen, Denmark).

[2] C. Ionita, F. Mehlmann, R. Schrittwieser, C. Lupu, P. Balan, H.W. Müller, M. Maraschek, V. Rohde, ASDEX Upgrade Team, R. Cavazzana, N. Vianello, M. Zuin, J.J. Rasmussen, V. Naulin. Simultaneous Measurements of Electrostatic and Magnetic Fluctuations in ASDEX Upgrade Edge Plasma. Accepted for publication in ICPP 2008 / Journal of Plasma and Fusion Research Series.

Corresponding author address:

Felix GennrichInstitute for Ion Physics and Applied Physics, University of InnsbruckTechnikerstrasse 25, A-6020 Innsbruck, Austriae-mail: [email protected]

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Electron energy distribution in the Njord RF plasma by means of an analogue differentiation method.

L.N. Mishra and Å. Fredriksen

Dep. Physics, Faculty of Science, University of Tromsø, N-9037 Tromsø, Norway.

Workshop topic: 13, other topics

The low-temperature plasma of the Njørd device is produced by means of a 13.56 MHz Helicon plasma source at 300-1 kW RF power. The plasma is expanding from the 13.5 cm di-ameter source into a 150 cm long chamber of 60 cm diameter. The key parameters of the plasma are studied with the electric probe measurement technique. The background plasma is character-ized in terms of ion saturation current, floating potential, plasma potential, electron temperature and plasma density. Ion energy and ion beams produced by a current-free double layer at the ex-pansion region have been studied by means of retarding field energy analyzers. However, to ob-tain information on electron energies and their interaction with the double layer, it is also neces-sary to characterize the electron energy distributions (EEDs). To derive the EEDs, the 2nd deriva-tive of the current characteristics of a swept probe must be obtained. For this purpose, an ana-logue differentiation circuit was built and tested. We report here the first electron energy distribu-tions measured in Njørd by this method.

Corresponding author address

Åshild Fredriksen Department of Physics and Technology University of Tromsø Tromsø, Norway e-mail: [email protected]

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Developments of Divertor Target-Imbedded Langmuir Probes for W7-X

M.Y. Ye 1, M. Laux1, S. Lindig2, R. Laube1, H. Greuner2

1Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald Wendelsteinstraß 1, D-17491, Greifswald, Germany

2Max-Planck-Institut für Plasmaphysik Boltzmannstraße 2, D-85748, Garching bei München, Germany

Workshop topic: 5, Robust probe tip constructions for high power loads

A target-imbedded array of electrostatic probes is a useful diagnostics to measure basic

plasma parameters close to the divertor targets. Therefore, the target- imbedded probes have to withstand the same or even higher thermal loads than the targets themselves. This means that, for long-pulse or steady-state operation, fixed probe tips have to be flush mounted and actively cooled [1]. In order to start plasma operation in 2014 it has been decided not to install the long pulse high-heat flux (HHF) divertor for the start of W7-X operation but to start in-stead with an inertially cooled divertor as the test divertor (TDU) for shorter plasma pulse op-eration. Afterward, the TDU will be replaced with the actively cooled HHF divertor for sta-tionary operation. With the aim of measuring the parameters of the plasma near the divertor plates it has been proposed to install imbedded probe arrays without active cooling into the TDU plates.

The TDU has been designed to withstand thermal loads up to 8MW/m2 for pulse opera-tion of the W7-X [2]. Therefore the imbedded probe arrays have to be designed not to result in a thermo-mechanical risk for the imbedding target. The design of the probes is still in the conceptual phase with the following main issues which concern thermo-mechanical design: (a) material selection for the probe and insulation layer, (b) investigation of thermal contact resis-tance between insulator and the probe and the imbedding target, (c) a finite element simula-tion of the different type of target-imbedded probe arrays, (d) test of a prototype target tile with imbedded probe arrays in the GLADIS facility [3]. At present the material of the probe is the same as that of the imbedding target (fine grain graphite). AlN has been chosen to insu-late the probes electrically from the imbedding target and from each other. The thermal resis-tance between graphite and AlN were measured under different contact pressures. The thermo-mechanical behaviour of the different types of target-imbedded probe arrays has been investigated by the finite element method. Detailed results will be reported in this conference. References [1] M. Laux, et al., Contrib. Plasma Phys. 46 (2006), 392. [2] A. Peacock, et al., Progress in the design and development of a test divertor (TDU) for the start of W7-X

operation, Fusion Eng. Des. (2009), in press. [3] H. Greuner, et al., J. Nucl. Mat. . 367 (2007), 1444. Corresponding author address Dr. Minyou Ye Max-Planck-Institut Für Plasmaphysik Teilinstitut Greifswald Wendelsteinstraße 1, D-17491, Greifswald, Germany e-mail: [email protected], phone: +49-3834-882521

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Influence of Ion Larmor Radius on Radial Profile of Ion temperature Measured by Ion Sensitive Probe

K. Todoroki, N. Ezumi

Nagano National College of Technology, Nagano 381-8550, Japan

Workshop topic: 3. Techniques for measuring the ion temperature

Ion behavior in edge and divertor plasmas plays important role in such as heat load to plasma facing components caused by influx of plasma blobs or high-energy ions, which has large Larmor radius and high cross field transport efficiency.

In this paper, we discuss experimental results of radial profile measurement of ion temperature (Ti) by means of ion sensitive probe (ISP) method [1] in the liner plasma generator CTP-HC (Compact Test Plasma device with Hot Cathode), which can produce argon plasmas in steady state by using a heated LaB6 spiral coil cathode in magnetic field up to 0.1 T [2]. Typical plasma parameters are the electron density ne ~ 1-5 x 1018 m-3 and the electron temperature Te < 10 eV. The plasma diameter is about 0.02 m, which is comparable to the ion Larmor radius in the device. This situation is similar to that of scrape off layer and divertor of fusion devices containing high-energy ion.

So far, observed radial profiles of Ti clearly show high Ti at the edge of the plasma column compared with the inside. It is likely that the results imply an influence of large Larmor motion of high-energy ions. More detail analysis based on particle in cell simulations and ion energy distribution measurement using a retarding field energy analyzer will be discussed. References [1] I. Katsumata, Contrib. Plasma Phys. 36S (1996) 73. [2] N. Ezumi, Contrib. Plasma Phys. 48 (2008) 435. Corresponding author address Kano Todoroki Advanced Course of Production and Environmental System, Nagano National College of Technology 716 Tokuma, Nagano 381-8550, Japan e-mail: [email protected] , phone: +81 26 295 7080

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Electrostatic Probes for Studying Transport Properties in Tokamak Plasmas

K. Uehara1, Y. Sadamoto2, H. Amemiya3,Y. Nagashima4 and M. Sakamoto5

1 Naka Fusion Establishment, Japan Atomic Energy Agency, Naka 311-0193, Japan

2 Department of Science, Joetsu University of Education, Joetsu 943-8512, Japan 3 Department of Science, Chuo University, Tokyo 112-8551,Japan

4 Graduate School of Frontier Science, The University of Tokyo, Kashiwa 277-8561,Japan 5 RIAM, Kyusyu University, Fukuoka 816-8580, Japan

Workshop topic: 3, Technique for measuring the ion temperature An electrostatic probe is a simple and convenient diagnostic tool for measuring

the plasma density and temperature with high spatial and time resolution, whereby

the information of plasma useful to clarify the plasma properties is obtained.

The ion temperature measuring method using the electrostatic probe for studying

the transport properties in tokamak boundary plasma is reviewed. A measurement

technique of the ion temperature has been developed using the asymmetric double

probe and applied to the boundary plasma in TEXTOR and JFT-2M [1].

Recently, this method has been applied to the long-life tokamak, TRIAM-1M,

with a strong magnetic field as high as 7T. In JFT-2M, the reciprocating

Langmuir probe and the differential double probe have been applied to detect the

transport study such as GAM identification [3] as well as the magnetic surface

[4].

Here, based upon these results, a new type probe is proposed for the quick

diagnostic of core hot plasmas. Since the application of the electrostatic probe is

limited to low density and low temperature plasmas, we propose a

flight-type-probe (FTP), in which the probe circuit and memory elements is

installed in a capsule for data acquisition. The whole unit is injected into the core

plasma with a very fast speed to ensure a quick measurement of plasma

parameters in hot core plasmas. The data acquired are transmitted through an rf

antenna to outside observers and/or saved in CPU memories for later analysis [4]. References [1] eg. H. Amemiya and K. Uehara, Rev. Sci.Instrum. 65 (1994) 2607 [2] Y. Nagashima et al., Plasma Phys. Control Fusion 51 (2009) 065019 [3] K. Uehara et al. ,Jpn. J. Appl. Phys. 45(2006) L630 [4] K. Uehara, J. Plasma Fusion Res. 81 (2005) 483 (in Japanese). . Kazuya Uehara, Japan Atomic Energy Agency, Naka 311-0193, Japan e-mail:[email protected], phone: 81-29-270-7532

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Ion temperature measurements in the Tore Supra scrape-off layer

using a retarding field analyzer

M. Kočan, J. P. Gunn, J.-Y. Pascal and E. Gauthier

CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France

Workshop topic: 3, Techniques for measuring the ion temperature

The ion temperature iT in the tokamak scrape-off layer (SOL) is of key importance for

modelling the impurity release from, and estimation of the heat flux deposited on plasma

facing components, calculation of the classical drift flows, definition of the outer boundary

conditions in the core transport models, etc. A dozen techniques have been developed to

measure SOL iT . However, measurements of SOL iT are very sporadic and often subject to

large errors (see references in [1]). One of the only widely accepted diagnostics for SOL iT

measurements is the retarding field analyzer (RFA) [2].

A bi-directional RFA, mounted on a fast reciprocating probe drive, is used in Tore

Supra since 1999. Until now, the RFA performed 3220 reciprocations (up to 15 per single

discharge) up to 4 cm inside the last closed flux surface and in the plasma heated up 8.5 MW.

In addition to iT , the RFA measures simultaneously the SOL electron temperature eT , the ion

saturation current density and the parallel Mach number //M .

In the beginning of our talk, the instrumental effects of RFAs and their influence on Ti

measurements will be discussed. Consequently, an overview of systematic measurements of

SOL iT in Tore Supra SOL by the RFA will be given. This includes the scaling of SOL iT

and eT with the main plasma parameters such as the density, radiated power fraction

(including detached plasma), heating power, toroidal magnetic field, etc. Except at very high

densities or in detached plasmas, ei TT > in the Tore Supra SOL. First continuous ei TT /

profile from the edge of the confined plasma into the SOL, constructed using data from

different tokamaks, will be discussed. In addition, the first evidence of poloidal asymmetry of

the radial ion and electron energy transport in the SOL, similar to that of the particle transport

[3], and its implications for the ITER start-up phase will be addressed. The correlation of the

asymmetries of SOL iT and eT measured from both sides along the magnetic field lines with

changes of //M , important for the Mach probe theory [4, 5], will be discussed.

[1] M. Kočan et al., Plasma Phys. Control. Fusion 50 (2008) 125009

[2] M. Kočan et al., Rev. Sci. Instrum. 79 (2008) 073502

[3] J. P. Gunn et al., J. Nucl. Mater. 363-365 (2007) 484

[4] I. H. Hutchinson, Phys. Fluids 30 (1987) 3777

[5] J. P. Gunn and V. Fuchs, Phys. Plasmas 14 (2007) 032501

Corresponding author address

Martin Kočan

Institut de recherches sur la fusion magnétique, CEA Cadarache

F-13108 Saint-Paul-lez-Durance, France

Email: [email protected], Tel: 0033(0)442253608

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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A novel cylindrical probe for measuring the ion temperature in magnetized plasmas

W. Tierens1

, M.Komm2, J.Stöckel2,G.Van Oost1

1 Department of Applied Physics, Ghent University, 9000 Gent, Belgium

2Institute of Plasma Physics, Association EURATOM/IPP.CR, Prague, Czech Republic

Workshop topic: 3, Techniques for measuring the ion temperature

Using particle in cell (PIC) simulations, we calculated the ion current density on the surface of a cylindrical probe in a boundary plasma whose top is perpendicular to the magnetic field. This current decays nearly exponentially with distance to the probe top. Preliminary results using simulations with thermal plasmas indicate that the decay length associated with this exponential decay depends on the temperature, similar to the behaviour of the more technically complex segmented tunnel probe (STP) 1,2. Measuring this decay length can be done by adding at least 2 conducting rings of equal size on the cylinder and measuring the current collected by these rings.

As the ion current is measured, we expect that the temperature obtained from such a probe will be the ion temperature. More simulations to verify this are underway. If verified, this probe could potentially be used to measure the ion temperature with spatial resolution of a few Larmor radii and temporal resolution limited only by the speed of the data acquisition.

The STP has not been used to measure the ion temperature in large tokamaks because of unfeasibly large accuracy demands and technical difficulties associated with adding more than 2 segments. Results using thermal plasmas indicate that the dependency of the currents on the temperature may well be stronger than for the STP, thus reducing accuracy demands. Adding more than 2 segments on this probe would be extremely simple.

Correctly aligning this probe with the magnetic field is critical. The probe can be made to align itself spontaneously by allowing it to rotate in three dimensions (using some kind of joint) and inserting a piece of ferromagnetic material within the cylinder.

There may be a possibility to test this concept in a small-scale tokamak. References [1] M. Kočan , J. Skalný, R. Pánek, J. Stöckel, J. Gunn, S. Kuhn, Particle-in-Cell Simulations of the Segmented Tunnel Probe for Ion-Temperature Measurements in the Tokamak Scrape-off Layer. Proceedings of International Conference Nuclear Energy for New Europe (5-8 September 2005, Bled, Slovenia) [2] M. Kočan , R. Pánek, J. Stöckel, M. Hron, J.P. Gunn, R. Dejarnac, Ion temperature measurements in the tokamak scrape-off layer, Journal of Nuclear Materials 363–365 (2007) 1436–1440 Corresponding author address Wouter Tierens Ghent University Jozef Plateaustraat 22, 9000 Ghent, Belgium e-mail : [email protected]

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Particle Flux to Spherical Probe in Weak Magnetic Field

Y. Tomita and G. Kawamura

National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 Japan Workshop topic: 8. Probes in recombining and drifting plasmas

Absorption cross section of a spherical probe is studied in a uniform magnetic field, while absorption cross sections in the absence of magnetic field was expressed by using the OML (Orbit Motion Limited) theory1, 2. The OML theory, where energy and angular momentum of a charged particle are conserved in an infinite Debye length limit, has been widely applied to charging of a dust particle in space plasmas as well as laboratory plasmas.

In this study an orbit of a charged particle (an ion or an electron) heading to a biased spherical probe along the magnetic field is analyzed analytically and numerically. The orbit of a charged particle is deviated from a straight one along the magnetic field due to the electrostatic force by a biased probe, while the presence of a radial velocity moves the particle to the azimuthal direction due to the Lorentz force. The radial force balance of the particle between the Lorentz force, resulting from azimuthal velocity and axial magnetic field, and the centrifugal force determines the radial motion of a charged particle. Thus the magnetic field has the second order effect on the orbit in the absence of magnetic field. In this study by using the numerical calculations the approximated formula of the absorption cross-section is derived, where the lowest order of the effects of the magnetic field is included. This approach is applicable to the case where the Larmor radius of the charged particle is much smaller than the probe radius.

The charged particle with the same sign as the probe charge approaches closer to the probe than the orbit without magnetic field, indicating larger absorption cross-section than that without magnetic field. On the other hand the charged particle with the opposite sign of the probe charge leaves further the probe, indicating the absorption cross section smaller. These effects are remarkable for electrons because of their high mobility compared to plasma ions. Furthermore the orbit of the electron with lower energy is largely deviated due to the magnetic field. For example, the absorption cross-section of the electron with 20 eV in the magnetic field of 10 G decreases from 9.42 cm2 to 3.73 cm2 for the positively biased spherical probe of + 10 V with 1 cm radius. On the other hand, in the case of the probe with negative voltage of -10 V, the absorption cross-section increases from 1.57 cm2 to 1.66 cm2 for the same electron energy and magnetic field. The effects of shielding effect by plasmas are discussed. References [1] H. Mott-Smith and I. Langmuir, Phys. Rev. 28 (1926), 727. [2] J.E. Allen, Phisica Scripta, 45 (1992) 497. Corresponding author address Yukihiro Tomita National Institute for Fusion Science 322-6 Oroshi-cho, Toki 509-5292 Japan [email protected]

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Towards fast electron temperature measurementsin the SOL of ASDEX Upgrade

H.W. Muller1, J. Adamek2, J. Horacek2, C. Ionita3,F. Mehlmann3, V. Rohde1, and ASDEX Upgrade Team1

1 Max-Planck-Institut fur Plasmaphysik, EURATOM-Association, Garching, Germany2 Institute of Plasma Physics, Association EURATOM/IPP.CR, Prague, Czech Republic

3 Institute for Ion Physics and Applied Physics, University of Innsbruck,Association EURATOM-OAW, Austria

Workshop topic: 11. Probe applications in fusion-oriented devices

Only a small data base on fast electron temperature (Te) measurements in thescrape off layer (SOL) of midsize or large tokamaks exists although it is of interestfrom different points of view. Especially in ELMy H-mode the data base israther poor. In H-mode the Te evolution during ELMs close to the plasma facingcomponents and the fall off length into the limiter shadow are of interest. ELMinvestigations require a time resolution on the filament time scale which is about10µs. Te fluctuations are also related to turbulent radial particle transport Γr =〈Epolne〉/B. Here Epol is the fluctuation of the poloidal electric field (Epol =−∇Vpl, with plasma potential Vpl), ne the electron density fluctuation. Thesaturation current density jsat and floating potential Vfl can be measured easilywith probes even on short time scales. They are related to Vpl and ne via Vpl =Vfl + αTe with constant α ≈ 2.5− 3.1 (thermal distribution assumed) and ne =

jsat/(e√kB(Te + 3Ti)/mi) (D plasma). Vpl and ne are usually substituted by Vfl

and jsat assuming temperature fluctuations Te can be neglected. But, the effectof Te in ELM filaments has still to be investigated. Also in between ELMs or inL-mode discharges it is not much known about Te in midsize or large tokamaks.

In ASDEX Upgrade swept probes with frequencies up to 150 kHz were used toinvestigate Te in the SOL close to the outer limiter in H-mode. These measure-ments were accompanied by measurements of Vfl using Langmuir tips and Vpl bymeans of ball pen probes [1] with 2 MHz data acquisition. This allows to comparedifferent measurement techniques and to investigate the relations of Vfl, Vpl andTe on short time scales. It was already seen that Vfl and Vpl show different powerspectra [2]. Vfl has much more pronounced fluctuations at high frequencies. Arelation to Te will be investigated. A first estimate on the influence of Te on Γrwill be presented.

[1] J. Adamek et al., J. Nucl. Mater., doi:10.1016/j.jnucmat.2009.01.286[2] J. Adamek et al., 36th EPS Conference on Plasma Physics, Sofia, Bulgaria, 2009

Corresponding author adressHans Werner MullerMax-Planck-Institut fur PlasmaphysikBoltzmannstrasse 2, 85748 Garching b. Munchen, Germanyemail: [email protected] phone: ++49 (0)89 3299 1803

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Ball-pen probe measurements in L-mode and H-mode on ASDEX Upgrade

J. Adamek1, V. Rohde2, H. W. Müller2, B. Kurzan2, C. Ionita3, R. Schrittwieser3, F. Mehlmann3, J. Stöckel1, J. Horacek1, V. Weinzettl 1 and ASDEX Upgrade Team2

1Institute of Plasma Physics AS CR, v.v.i., Association EURATOM/IPP.CR, Prague, Czech Republic; 2MPI für Plasmaphysik, EURATOM Association, Garching, Germany;

3Institute for Ion Physics and Applied Physics, University of Innsbruck, Association EURATOM-ÖAW, Austria. Workshop topic: 11. Probe applications in fusion-oriented devices

The design of the ball-pen probe (BPP) was developing during the recent years [1,2]. Mean-while the BPP was used in the scrape-off layer (SOL) of several fusion devices as CASTOR, RFX and ASDEX Upgrade (AUG). On AUG, the latest BPP measurements with the improved probe head from IPP Prague were devoted to the investigation of the temporal evolution of the plasma and floating potential during ELM (edge localized modes) .

The direct measurements of the plasma potential with BPPs are based on the assumption that the electron and ion saturation currents flowing to each collector are balanced and its ratio R=Isat

–/Isat+ is close to one [1]. This was not yet proved during ELM events. However, the additional

measurements on ASDEX Upgrade confirmed that these currents are really balanced and their ratio remains close to one also during the ELM events.

ELMs are usually studied in the SOL by means of standard Langmuir probes, providing the floating potential and the ion saturation current Isat

+. However, with such probes it is not straight-forward to evaluate the plasma potential. ELMs show a pronounced fine structure, so-called fila-ments, where the electron temperature might vary strongly. Under these circumstances it is advan-tageous to measure the plasma potential and the floating potential by means of both BPPs and Langmuir probes. We have performed several discharges in ELMy H-mode with neutral beam in-jection (NBI). It was found that the difference between the plasma and floating potential, Φpl – Vfl, is systematically positive as expected from Φpl = Vfl+alpha*Te. The difference, divided by a suitable factor, can be taken as a measure for the electron temperature, if the electron distribution function is assumed to be Maxwellian also during ELM events.

The first comparative measurements of the radial profiles of the electron temperature in L-mode provided by the difference (Φpl – Vfl )/alpha and edge Thomson scattering will be also pre-sented. References

[1] J. Adámek, J. Stöckel, M. Hron, J. Ryszawy, M. Tichý, R. Schrittwieser, C. Ionita, P. Balan, E. Martines, G. Van Oost, Czechoslovak J. Phys. 54 (2004) C95-C99.

[2] J. Adamek, V. Rohde, H.W. Müller, A. Herrmann, C. Ionita, R. Schrittwieser, F. Mehlmann, J. Stöckel, J. Horacek, J. Brotankova, Journal of Nuclear Materials 390-391 (2009) 1114-1117.

Corresponding author address

Jiri Adamek Institute of Plasma Physics AS CR, v.v.i. Za Slovankou 3, 182 00, Prague 8, Czech Republic; e-mail: [email protected] , phone: +420 266 052 961

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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A Probe Head for Simultaneous Measurements of Electrostatic and Magnetic Fluctuations in ASDEX Upgrade Edge Plasma

R.W. Schrittwieser1, C. Ionita1, N. Vianello2, H.W. Müller3, F. Mehlmann1, M. Zuin2, V. Naulin4, J.J. Rasmussen4, V. Rohde3, R. Cavazzana2, C. Lupu1, M. Maraschek3, C. Maszl1,

ASDEX Upgrade Team3 1Association EURATOM/ÖAW, Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

2Association EURATOM/ENEA, Consorzio RFX, Padova, Italy 3Association EURATOM/IPP, Max-Planck-Institute for Plasma Physics, Garching, Germany

4Association EURATOM/RISØ-Technical University of Denmark, Roskilde, Denmark

Workshop topic: 11, Probe applications in fusion-oriented devices

In ASDEX Upgrade (AUG) a new probe head was used for simultaneous measurements of electrostatic and magnetic fluctuations in the edge plasma region. The probe head consisted of a cylindrical graphite case of about 60 mm diameter and 115 mm length. On the front side six graphite pins of 1 mm diameter and 2 mm length are mounted isolated from each other by boron nitride, which is retracted to avoid damages by the radiation from the plasma. The six pins are arranged in two rows of three pins each with a distance of 10 mm from each other. In poloidal direction the two rows of pins are situated above each other with a distance of 10 mm in between. One of the probe pins protrudes by 3 mm in radial direction.

With this arrangement the poloidal and radial electric field components, the ion satura-tion current and the current-voltage characteristic can be registered simultaneously. The elec-tric field components are calculated from the difference of the floating potentials of the re-spective probe pins, assuming equal electron temperatures on the pins. By using the poloidal electric field and the ion saturation current (as measure for the plasma density), the radial E×B-driven flux can be derived. Taking into account the radial electric field, also the Rey-nolds stress and the radial flux of the poloidal momentum can be determined. The upper cut-off frequency is about 100 kHz.

Inside the graphite case, 20 mm behind the front side, a magnetic sensor is mounted by which the time derivatives of the three components of the magnetic field are measured. The sensor consists of three coils produced by winding a 0,2 mm diameter wire around a small par-allelepiped-shaped support of Vespel of 7×7×8 mm3 dimensions. During the AUG discharges of 7 s lengths the probe head is inserted up to three times for 100 ms each by the midplane manipulator into the scrape-off layer outside the last closed flux surface. Measurements were carried out during ELMy H-mode discharges, during and in between type-I ELMs, during L-mode discharges and during transitions between the two modes [1,2].

References

[1] C. Ionita, N. Vianello, H.W. Müller, F. Mehlmann, M. Zuin, V. Naulin, J.J. Rasmussen, V. Rohde, R. Cavazzana, C. Lupu, M. Maraschek, R.W. Schrittwieser, P.C. Balan, ASDEX Upgrade Team, J. Plasma and Fusion Research Series, in print.

[2] N. Vianello, V. Naulin, R. Schrittwieser, H.W. Müller, M. Zuin, C. Ionita, J.J. Rasmussen, F. Mehlmann, V. Rhode, R. Cavazzana, M. Maraschek, C. Lupu, ASDEX Upgrade team, Phys. Rev. Lett., to be submit-ted.

Corresponding author address

Roman Schrittwieser Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstr. 25, A-6020 Innsbruck, Austria e-mail: [email protected], phone: +43 512 507 6244

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Mass-sensitive ion probe for edge plasma characterization on the tokamak ISTTOK

I. S. Nedzelskiy, C. Silva, P. Duarte, H. Figueiredo, H. Fernandes

Associação EURATOM/IST, Instituto de Plasma e Fusão Nuclear, Av. Rovisco Pais 1049-001 Lisboa, Portugal.

11, Probe applications in fusion oriented devices

The principle of the mass-sensitive ion probe (MSIP) operation consists in time-of-flight (TOF) analysis of the ions in the burst excited by short (µs-range) voltage pulse applied to small grid immersed into the plasma. The ions in the burst propagate along magnetic field lines of the tokamak with velocities determined by the value of the applied voltage and ions mass/charge (M/Z) ratio. The separated along some distance (TOF path) from the grid bursts of ions of different species and charges are detected by retarding field energy analyzer (RFEA). This contribution presents description of MSIP design and first operation on the tokamak ISTTOK. The preliminary results of the obtained mass-spectra will be presented and discussed also.

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Probe Diagnostics in Microwave Plasma Jets at Atmospheric Pressure

M. A. Razzak, S. Saito and S. Takamura

Faculty of Engineering, Aichi Institute of Technology, Toyota 470-0392, Japan

Workshop topic: 12, probe diagnostic in technological plasmas

Recently, a rapid interest is growing for atmospheric-pressure plasmas in the field of material science, and as a new source for fundamental research on plasma-wall interaction in next-generation fusion devices, such as ITER and DEMO. In this regard, the design of stable and efficient plasma generators is of high demand. For designing such plasma sources by optimizing the discharge performance, the generated plasma parameters, such as electron temperature and electron density, must be known. The Langmuir probe is the most commonly used diagnostic tool to determine the plasma parameters under a variety of plasmas. But the investigation of measured probe characteristic of collisional plasmas under atmospheric pressure is quit difficult due to the lack of high-pressure probe theories. In this work, we have analyzed the measured probe characteristics of microwave plasma jets at atmospheric pressure using the recently developed high-pressure probe theory [1] in order to determine the generated plasma parameters. The single-probe measurement is applied to a rectangular waveguide-based 2.45GHz argon and helium plasmas at atmospheric pressure with a moderate microwave power of less than 500W by applying the TIAGO (Torche à Injection Axiale sur Guide d'Ondes, in French) nozzle [2].

The electron temperature of Ar plasmas is found almost constant of K, while the electron density is found to be slightly decreasing from to m-3 over the range of height up to 30 mm from the nozzle head. For the He plasmas, on the other hand, the electron temperature is found from to K over the range of height up to 20 mm from the nozzle head and then decreases to about K from 20 mm onward, and the electron density is found from to m-3 over the range of height up to 30 mm from the nozzle head. It is observed that the high-pressure single-probe theory provides some over estimation of electron temperatures in both Ar and He plasmas. This may be due a smaller electron to ion saturation currents ratio in I-V characteristics than what is expected from the high-pressure probe theories. The small electron to ion saturation currents ratio comes from the limited electron saturation current caused by the insufficient contact of plasma with the reference electrode having small contact surface like TIAGO nozzle. This problem may be solved by analyzing the measured probe characteristics applied to asymmetric double probe theories which will be discussed elsewhere [3].

4105.2 ×19105.2 × 19105.1 ×

4104 × 4105.6 ×19105.2 ×

19105.7 × 19105.0 ×

References [1] M. R. Talukder, D. Korzec and M. Kando, J. Appl. Phys., 91 (2002), 9529. [2] M. Moisan, Z. Zakrzewski and J. C. Rostaing, Plasma Sources Sci. Technol., 10 (2001), 387. [3] S. Saito, S. Takamura and M. R. Talukder, will be presented in IWEP 2009 (21-24 September 2009,

Innsbruck, Austria). Corresponding author address

M. A. Razzak Faculty of Engineering, Aichi Institute of Technology, Toyota 470-0392, Japan E-mail: [email protected] Phone: +81-80-3676-5865

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Double probe measurements in magnetically enhanced RF plasma source at pressures below 0.1 Pa

J. Kousal1, M. Tichý2, O. Šebek2, J. Čechvala1, H. Biederman1

1Charles University in Prague, Faculty of Mathematics and Physics, Department of Macromolecular Physics, V Holešovičkách 2, 180 00 Prague, Czech Republic

2Charles University in Prague, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2,180 00 Prague, Czech Republic

Workshop topic: 12. Probe diagnostic in technological plasmas

The majority of plasma polymerization techniques for thin film depositions are per-formed at pressures above 1 Pa [1]. Under these pressures the film-forming species undergo a significant number of collisions before arriving at the substrate. This complicates utilization of the directional effects of deposition. Therefore a plasma polymerization source operating at pressures below 0.1 Pa was developed.

The plasma source consists of the axially pumped glass tubular reactor with point feed of the working gas (argon+monomer) via a quartz capillary. The gas pressure quickly drops downstream of the capillary orifice to 10–1 Pa or less (typically 0.06 Pa). The 13.56 MHz RF power (2-30 W) is delivered to ring electrodes outside the reactor. The plasma density and confinement is enhanced by a magnetic field of the ring of permanent magnets forming a double ”magnetic nozzle”.

The double probe method [2] was used to determine the plasma density and temperature of the ”hot” electrons. In this study only argon without monomer admixture was used. The measured plasma density was in the range 1012-1016 m–3 and the hot electron temperature was from 3 to 30 eV, in dependence on the probe position, working pressure and RF power. Gen-erally, the plasma density was found to drop almost exponentially downstream of the mag-netic circuit position. The electron temperature was found to be the highest near the magnetic circuit and in the afterglow region. The supplementary data on probes floating potential dif-ference suggest significant electric fields (103 V.m–1) present near these regions. When higher working pressures (up to 0.5 Pa) were used, the character of the plasma was rather similar to plasma in the usual capacitively coupled discharges [3]. The differences to the case of n-hexane as a monomer admixture are discussed.

References [1] H. Biederman (ed.), Plasma Polymer Films, Imperial College Press, London, (2004) [2] R. Hippler, S. Pfau, M. Schmidt, K.H. Schoenbach (ed.), Low Temperature Plasma Physics: Fundamental

Aspects and Applications, Wiley-VCH, (2001) [3] M.A. Lieberman, A.J. Lichtenberg, Principles of plasma discharges and materials processing, Wiley,

(1994) Corresponding author address

Jaroslav Kousal Charles University in Prague Faculty of Mathematics and Physics V Holešovičkách 2,180 00 Prague, Czech Republic e-mail: [email protected], phone: +420 2 2191 2256

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Spatial Distribution of Plasma Parameters in DC-Energized Hollow Cathode Plasma Jet

S. Leshkov, P. Kudrna, M. Chichina, J. Klusoň, I. Picková, M. Tichý

Charles University in Prague, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 180 00 Praha 8, Czech Republic

Workshop topic: 12. Probe diagnostic in technological plasmas

Plasma jet systems with dc hollow cathode are well known as deposition sources. The system with cylindrical symmetry, which used in our experiments, can work at low pressure down to several Pa. The UHV vacuum chamber pumped by turbomolecular pump to ultimate pressure in the order of 10-6 Pa provides good cleanliness and hence the studied processes are well reproducible. The water cooled hollow cathode with internal diameter of 4 mm is powered by DC power supply in current stabilizing mode. The mixture of argon and oxygen is used as working gas. In combination with titanium hollow cathode it provides deposition of titanium oxide thin films at the substrate placed downstream below the cathode. Our recent study of several plasma jet systems including atmospheric pressure ones is presented in [1].

Radial profiles of plasma parameters measured by cylindrical Langmuir probe, namely plasma density, electron mean energy, plasma potential and floating potential are presented. The plasma density is determined from the slope of the plot of the square of electron current vs. probe voltage in the electron accelerating regime while the mean electron energy is derived from the integral of electron energy distribution function. For all radial profiles the pressure in the chamber in the range from 5 to 70 Pa is used as parameter.

In our contribution there are compared plasma parameters at two scenarios. In the first scenario argon and oxygen are mixed upstream of the hollow cathode. In the second scenario only pure argon flows through the hollow cathode and the mixture with the same composition is created by adding the oxygen separately into the chamber. The first - upstream mixed - Ar+O2 scenario yields electron densities with the maximum of 1018 m-3 below the nozzle. That is approximately by one order of magnitude higher compared to the second scenario. The mean electron energies are below 1 eV and up to 5 eV in the first and the second scenario respectively.

Further there is studied the time dependence of plasma parameters when changing from the first to the second argon/oxygen scenarios. It is shown that self-cleaning of the oxidized inner surface of the nozzle (created in the first scenario by the presence of oxygen) by the hollow cathode pure argon discharge lasts approximately 25 minutes in the presented system.

References [1] M. Tichý, Z. Hubička, M. Šícha, M. Čada, J. Olejníček, O. Churpita, L. Jastrabík, P. Virostko, P. Adámek, P. Kudrna, S. Leshkov, M. Chichina, Š. Kment, Plasma Sources Sci. Technol. 18 (2009), 014009.

Corresponding author address

Milan Tichy Charles University in Prague Faculty of Mathematics and Physics Department of Surface and Plasma Science V Holesovickach 2, 180 00 Praha 8, Czech Republic Telephone: +420 221 912 305 e-mail: [email protected]

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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A Study of Plasma Parameters in Hollow Cathode Plasma Jet in Pulse Regime

P. Kudrna1,2, J. Klusoň1,2, I. Picková1, Z. Hubička2, M. Tichý1

1Charles University in Prague, Faculty of Mathematics and Physics, Department of Surface and Plasma Science, V Holešovičkách 2, 180 00 Praha 8, Czech Republic

2Institute of Physics, Academy of Sciences of the CR, v.v.i., Na Slovance 2, 18221 Praha 8, Czech Republic

Workshop topic: 12. Probe diagnostic in technological plasmas

The low pressure hollow cathode plasma jet is based on the hollow cathode discharge principle described in [1]. Its well defined plasma channel is especially suitable for deposition of different materials, e.g. tribological layers of TiO2 [2], piezoelectric layers [3] of ZnO or ferroelectric layers of SrTiO3 (STO) and BaxSr1-xTiO3 (BSTO) ceramics [4] and also for deposition on complicated e.g. non-concave substrates [5]. The operation in pulsed regime is advantageous for the deposition of non-conductive layers to prevent arcing, to lower substrate heating and to increase the plasma density during the on-time. By the simultaneous control the ion/neutral flux to the substrate the compressive stress in the film is reduced [6].

Our plasma jet system is installed in UHV stainless steel chamber. Water cooled titanium nozzle powered as a hollow cathode is reactively sputtered by the bombardment of positive Ar ions. Negative pulses are created using the capacitor reinforced dc power supply and the IGBT switch. For the stability of the pulsed discharge a 3.8 kΩ resistor was connected across the switch. Plasma is studied by means of time resolved movable Langmuir probe. The plasma potential, electron density and temperature were evaluated in dependence of the position and time.

During the pulse-on time the electron density rises up to 1018 m-3 which is much higher density than that obtained in continuous regime in similar system [3]. The decay of the electron density is influenced by the weak background dc discharge necessary for pulsed discharge stability. The electron temperature remains low within the whole discharge period.

References [1] M. Tichý, M. Šícha, L. Bárdoš, L. Soukup, L. Jastrabík, K. Kapoun, J. Touš, Z. Mazanec, R. Soukup,

Contrib. Plasma Phys., 34 (1994), 765. [2] L. Bárdoš and H. Baránková, Surf. Coat. Tech., 146-147 (2001), 463. [3] M. Čada, Z. Hubička, P. Adámek, P. Ptáček, H. Šíchová, M. Šícha, L. Jastrabík, Surf. Coat. Tech.,

174-175 (2003), 627. [4] Z. Hubička, M. Chichina, A. Deyneka, P. Kudrna, J. Olejníček et. al., Journal of Optoelectronic and

Advanced Materials, 9 (2007), 875. [5] M. Čada, Z. Hubička, V. Kuliovsky, P. Adámek, J. Olejníček, P. Boháč, Surf. Coat. Tech.,

200 (2006), 3861. [6] L. Bárdoš and H. Baránková, Surf. Coat. Tech., 133-134 (2000), 522.

Corresponding author address

Pavel Kudrna Charles University in Prague Faculty of Mathematics and Physics V Holešovičkách 2,180 00 Prague, Czech Republic e-mail: [email protected], phone: +420 2 2191 2225

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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Development of Asymmetric Double Probe Formula

and Its Application for Collisional Plasmas S. Saito

1, S. Takamura

1 and M.R. Talukder

2

1Faculty of Engineering, Aichi Institute of Technology, 470-0392 Toyota, Japan

2Department of Applied Physics and Electronics, University of Rajshahi, Rajshahi-6205, Bangladesh

Workshop topic: 12, probe diagnostic in technological plasmas

It has been known that there are some difficulties to interpret the I-V

characteristics of single probe for strongly magnetized plasmas[1,2] and detached

recombining plasmas[3]. In these cases, it is observed that the ratio of electron to ion

saturation current following to a single probe is smaller than what is expected from the

standard theory. Consequently the characteristics give over estimation of the electron

temperature. To avoid these problems, asymmetric double probe theory is applied to the

single probe characteristics.

Plasmas produced in atmospheric pressure range are expected to be applied to

material processing technology and as a new source for studies on plasma-wall

interaction, in which high particle and heat flux is envisaged. For these applications, it

has been recognized that a similar phenomena for I-V characteristics of single probe

would occur. The I-V curves distorted by the limitation of electron saturation current

gives electron temperature, for example, about 4eV which is much higher than expected.

The common feature of such a distortion comes either from a limitation of electron

current by some reasons or a weak contact of the target plasma with the reference

electrode for single probe since the large electron probe current is ensured by the

possible large ion current at the interfere between the target plasma and the reference

electrode surface. Therefore, an idea to solve this inconsistency is to interpret the I-V

curves as asymmetric double probe rather than single probe.

An electrostatic single probe characteristics in a dense, slightly ionized plasma is

studied by Su et al.[4] and Cohen[5], and some formula which one can easily be applied

for single probe diagnosis are introduced[6]. We extend Cohen’s theory to have

asymmetric double probe formula with the above-mentioned motivation. The new

theory for collisional plasmas has been applied to avoid an overestimation of the

electron temperature.

References [1] K. Günther, Contrib. Plasma Phys. 30 (1990), 51.

[2] K. Günther, A. Herrmann, M. Laux, P. Pech, H.-D. Reiner, J. Nucl. Materials 176-177 (1990), 236.

[3] R. D. Monk, A. Loarte, A. Chankin, S. Clement et al., J. Nucl. Materials 241-243 (1997), 396.

[4] C. H. Su, S. H. Lam, Phys. Fluids 6 (1963), 1479.

[5] I. M. Cohen, Phys. Fluids 6 (1963), 1492.

[6] M. R. Talukder, D. Korzec, M. Kando, J. Appl. Phys. 91 (2002), 9529.

Corresponding author address

Seiki Saito

Faculty of Engineering, Aichi Institute of Technology

1247, 470-0392, Japan

e-mail: [email protected], phone: +81-0572-58-2351

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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Electrical probe diagnostics for the KSTAR

J.-G. Bak, S.G. Lee, J. Y. Kim and KSTAR project team

National Fusion Research Institute, Daejeon,305-333, KOREA

Workshop topic: 11, Probe applications in fusion-oriented devices

Electrical probe diagnostics (EPDs) for the Korea Superconducting Tokamak Advanced Research (KSTAR), which are composed of two fast reciprocating Langmuir probe assemblies (FRLPAs) and fixed edge Langmuir probe array (ELPA), are required to study on edge plasma during a plasma discharge in the KSTAR machine. The FRLPA measures spatial profile of plasma parameters in the divertor/SOL (scrape-off layer) region and the ELPA measures plasma basic parameters and their poloidal profiles in the plasma-surface interaction regions such as inboard limiter and divertor. Considerable progress on the EPDs for their installation in the KSTAR machine has been done. In this work, details on the KSTAR EPDs will be described and current activities on the KSTAR EPDs, such as the performance test of the prototype and the installation, will be presented. This work was supported by the Korean Ministry of the Education, Science and Technology under the National Fusion Project Contracts.

Corresponding author address

Jun-Gyo Bak National Fusion Research Institute 113 Gwahangno, Yusung-Gu, Korea e-mail: [email protected], phone: +82-42-870-1644

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Multi-channel analyzer investigations of ion flux at the target surface in Pilot-PSI

M. L. Solomon1, I. Mihaila1, V. Anita1, C. Costin1, G. Popa1,

H. J. van der Meiden2, R. S. Al2, M. van der Pool2 , G. J. van Rooij2, N. J. Lopes-Cardozo2, J. Rapp2

1Faculty of Physics, Al. I. Cuza University, Association EURATOM-MEdC,

11 Carol I Blvd., 700506-Iasi, Romania 2FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, Trilateral Euregio Cluster,

P.O. Box 1207, 3430 BE Nieuwegein, The Netherlands, www.rijnhuizen.nl Workshop topic: 11, probe applications in fusion-oriented devices Pilot-PSI is a magnetized linear plasma device designed for investigations of plasma-surface interaction at ITER relevant parameters. A cascaded-arc plasma source operated in argon or/and hydrogen generates a high-density plasma that is magnetically confined on the vessel’s axis, resulting a plasma column of about 1-2 cm in diameter which interacts with a solid target. Both optical (Thompson scattering) and electrical (probes) experiments showed strong radial gradients of density and temperature in the plasma column. These gradients might affect the interaction of the plasma column with the target. An electrostatic multi-channel analyzer was constructed to study such effects by measuring the 2D spatial distribution (polar-plane coordinates) of the ion flux at target surface. The analyzer was placed in the center of the Pilot-PSI target and current-voltage characteristics were drawn for five collectors disposed at different radial positions. The ion flux was estimated from the ion part of the current-voltage characteristic for each collector position. At plasma densities up to 1·1020 m-3, we measured ion fluxes of 1022 - 1023 ions/m2s. We measured a difference of a factor of four between the maximum ion flux in the center of the target and the flux at the edge, at a radial position of 1 cm. References

[1] V. P. Veremiyenko, “An ITER-relevant magnetized hydrogen plasma jet”, PhD. thesis,

Eindhoven Technical University, the Netherlands (2006)

[2] G. J. H. Brussaard, PhD. thesis, Eindhoven Technical University, the Netherlands (1999)

[3] D.E. Post and R. Behrich ”Physics of Plasma-Wall Interactions in Controlled Fusion”, NATO

ASI Series B: Physics Vol. 131, Plenum Press, New-York and London (1984)

[4] G. F. Matthews, Plasma Phys. Control. Fusion 36 (1994) 1595 – 1628

[5] J. Wesson, ”Tokamaks” Clarendon Press, Oxford (1987)

Corresponding author address Marius Lucian Solomon University Alexandru Ioan Cuza Street Carol I, No. 11, ZIP 700506, Town Iasi, Country Romania e-mail: [email protected] phone: +40 (232) 201188

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Ion Temperature Measurements of the LHD Stochastic Magnetic Boundary Plasma Using an Ion Sensitive Probe

N. Ezumi1, K. Todoroki1, T. Kobayashi2, N. Ohno2, K. Sawada3, M. Kobayashi4,

S. Masuzaki4 and Y. Feng5

1Nagano National College of Technology, Nagano 381-8550, Japan 2Nagoya University, Nagoya 464-8603, Japan 3Shinshu University, Nagano 380-8553, Japan

4National Institute for Fusion Science, Toki 509-5292, Japan 5Max-Planck-Institut fuer Plasmaphysik, D-17491 Greifswald, Germany

Workshop topic: 11. Probe applications in fusion-oriented devices

Understanding of ion dynamics in edge and divertor plasmas has been strongly required in order to improve confinement and to achive high performance plasma in magnetic fusion experimental devices. Ion temperature (Ti) is one of the key parameters for characterizing the ion behaviours. The first reliable measurement of Ti of the boundary plasma in the Large Helical Device (LHD) was done by means of ion sensitive probe (ISP) method [1,2]. The satisfactory current-voltage characteristics of the ion collector for evaluating the ion temperature were obtained at the divertor leg. However, Ti profiles have not been measured in the stochastic magnetic boundary layer, which equipped intrinsically in the scrape-off layer in the so-called ergodic divertor configuration tokamaks and heliotron-type devices.

Recently, we have developed a movable multiple functions probe which consists of Mach probes and an ISP for revaling the detail structure in the boundary plasma region of LHD. So far, evaluated Mach numbers using the ion saturation current clearly show the existence of plasma flow alternation [3].

In this paper, we report the result of Ti measurement using the ISP in the multifuncition probe in the LHD stochastic magnetic boundary. Compared with the boundary layer of tokamaks, the magnetic field structure of the LHD boundary region is much complicate. Though it is difficurt to arrange a probe paralled to the magnetic field line during the probe traveling, ISP has the advantage for the oblique magnetic field owing to the structure. Obtained Ti shows almost same temperature with electron on the inside of the stochastic boundary layer. On the other hand, Ti on the outside the layer indicate higher temperature than that of electron. The measured temperature profiles at the edge of the stochastic boundary are qualitatively consistent with the results of EMC3-EIRENE simulation [4,5].

This work was partially supported by NIFS Collaborative Research Program (NIFS05KLPP009, NIFS08KLPP314) and by NIFS/NINS under the project of Formation of International Network for Scientific Collaborations. References [1] I. Katsumata, Contrib. Plasma Phys. 36S (1996) 73. [2] N. Ezumi, S. Masuzaki, N. Ohno et al., J. Nucl. Mater. 313-316 (2003) 696. [3] N. Ezumi, T. Kobayashi, N. Ohno et al., Experimental Observation of Plasma Flow Alternation in the LHD

Stochastic Magnetic Boundary, to be appeared in Plasma and Fusion Research. [4] M. Kobayashi, Y. Feng, S. Masuzaki et al., J. Nucl. Mater. 363-365 (2007) 294. [5] Y. Feng, M. Kobayashi, T. Morisaki et al., Nucl. Fusion 48 (2008) 024012. Corresponding author address Naomichi Ezumi Department of Electronics and Control Engineering, Nagano National College of Technology 716 Tokuma, Nagano 381-8550, Japan e-mail: [email protected], phone: +81 26 295 7080

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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Application of floating hairpin probe in strongly magnetized plasma S. K. Karkari1, G. S. Gogna1, D. Boilson1, M. M. Turner1 and A. Simonin2

1NCPST,Dublin City University, Collins Avenue, Dublin 9, Ireland

2Department CEA/DSM/DRFC, CEA-Cadarache, 13108 ST PAUL-LEZ-DURANCE France

Workshop topic: 11, Probe application in Fusion oriented devices The plasma present in front of the plasma electrode in a negative ion source, operated under ITER required specifications is very complicated. The main complication arises due to the presence of a very strong magnetic field, B = 1200 G.cm in the filter field region, which is required in order to reduce the number of co-extracted electrons and reduce the destruction of H- ions by fast electrons. The understanding of the physics in the filter field region of the ion source is very important as this region is where negative ions are generated and extracted. For accurately determining electron densities in this complex plasma, a floating hairpin probe is applied for the first time on the KAMABOKO III ion source, at the MANTIS test bed at CEA Cadarache. The technique is based on measuring the probes resonance frequency (few GHz) shift in plasma with respect to that obtained in vacuum. The resonance frequency is proportional to the permittivity of the medium filling the space between the wires of the hairpin resonator. Advantage of using this technique is that the probe is electrically floating hence perturbation to the plasma is minimal. Preliminary investigation on probe’s orientation with respect to the external magnetic field showed no shift in the probes characteristic resonance frequency. However we observe significant increase in the width of the resonance peak. The resonance signal diminished when ; (i) the probes resonance frequency fr ~ fpe (electron plasma frequency) due to transfer of energy from the oscillating E-filed to the electrons and (ii) the oscillating electric field between the hairpin prongs is perpendicular to the external B-field due to increased collision of electrons in the volume. Using this technique electron density was obtained at 4 cm from the extraction grid at modest operating powers up to 16 KW. The results show monotonic increase in electron density with operating powers. The highest density is obtained at the center of the discharge where the B-field is weak as compared to the edge. Also obtained is the effect of grid bias on the local electron density which was found to decrease with the positive bias on the grids. [1] R. L. Stenzel, Rev. Sci. Instrum. 47, 603, 1976 [2] S. K. Karkari, C. Gaman, A. R. Ellingboe, I. Swindell and J. W. Bradley, Meas. Sci. Technol. 18 (2007) 2649–2656 Acknowledgement: This work was supported by Enterprise Ireland grant TD/07/335 and Association EURATOM DCU Fusion grant FU07-CT-2007-00052. Corresponding author address Shantanu Karkari National Centre for Plasma Science and Technology, Dublin City University Collins Avenue, Dublin 9, Republic of Ireland. e-mail: [email protected], phone: (+353 1 700 5037)

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Plasma Potential and Electron Energy Distribution Function Measured by Langmuir Probe in Tokamak Edge Plasma

Tsv. K. Popov1, P. Ivanova1, J. Stöckel2 and R Dejarnac2

1 Faculty of Physics, St. Kl. Ohridski University of Sofia,

5 J. Bourchier Blvd., 1164 Sofia, Bulgaria 2 Institute of Plasma Physics, Academy of Sciences of the Czech Republic v.v.i.

Za Slovankou 3, 182 00 Prague 8, Czech Republic

Workshop topic: 11. Probe applications in fusion-oriented devices

The first derivative Langmuir probe (LP) method for processing the electron part of the

current–voltage (IV) characteristics measured in strongly magnetized plasma for evaluation of the

electron energy distribution function (EEDF) will be presented and discussed. Special attention

will be paid on the precise evaluation of the plasma potential.

Results from measurements in tokamak edge plasma will be presented. The comparison of

the results obtained with perpendicular and parallel to the magnetic field probes as well as the

results given by the classic method leads to a satisfactory agreement.

The results presented demonstrate that the procedure proposed allows one to acquire

additional plasma parameters using the electron part of the current–voltage LP characteristics in

magnetized plasma measurements than in the classical method, which uses the ion part of the IV

characteristic.

The work is in implementation of task P4 of Work Plan 2008 of the Association

EURATOM/INRNE.BG in collaboration with the Association EURATOM/IPP.CR, Prague,

Czech Republic and Contract #60/2009 St. Kl. Ohridski University of Sofia SF.

Corresponding author address Tsviatko Popov Faculty of Physics St Kliment Ohridski University of Sofia 5, James Bourchier Blvd 1164 Sofia, BULAGARIA [email protected] Cell phone +359 888 33 91 21 Phone +359 2 81 61 738

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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A New look at Fluctuation Driven Particle Flux inferred by Electrostatic Triple Probes

C.Ribeiro

Department of Physics at Faculty of Science and Technology, New University of Lisbon, 2829-516, Caparica,

Portugal

Workshop topic: 1,2,4,7,11

Plasma anomalous transport severely reduces the economical attractiveness of any possible fusion energy reactor based on magnetically confined thermonuclear plasma. Therefore, to understand and control the major mechanisms of this transport, mainly due to the anomalous particles losses, is vital to ameliorate a potential fusion reactor scenario.

In this context, plasma edge is naturally a key area of research in which considerable effort has been allocated to theory and experiments in auxiliary heated plasma confinement devices such as tokamaks.

We reported here data of a triple Langmuir probe located at the plasma edge and scrap-off layer of TCABR tokamak [R=0.615m, a=0.18m, Ip≤120kA, ne(bar)≤4x1019m-3, Te(0)≤600eV, Ti(0)≤400eV, discharge duration of 100ms, approximately, and solid circular poloidal divertor]. Plasma density, electric fields, electron temperature, and respectively fluctuations, all were simultaneously measured with high spatial and temporal resolution. Corrections in the way fluctuation driven particle flux is inferred via the poloidal electrical field and density fluctuations are also presented. Here, the finite geometry of the electrodes tips and the use of the more physical plasma potential instead of floating potential between the two tips alter the first parameter while and the finite electrical sheath formed at the probe ion collecting area affects the second, and an analytical expression to calculated the corrected plasma density based on the Hutchinson model for collisionless plasmas[1] is proposed for this context. Finally, the correlation between the dynamic of the fluctuation driven particle flux with and the global plasma parameters on discharges under auxiliary heating via Alfvén Waves (AW) will be also discussed.

References [1] I. H. Hutchinson, Principles of plasma diagnostics, 2nd edition, Cambridge University Press, pg.66, (2002).

Corresponding author address Celso Ribeiro Department of Physics at Faculty of Science and Technology, New University of Lisbon, 2829-516, Caparica, Portugal e-mail: [email protected], phone: (+351-967817964)

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Emissive Probes for the Diagnostics of the Plasma Potential in Fusion Experiments

C. Ionita1, R. Schrittwieser1, C. Silva2, H. Figueiredo2, C. Maszl1, R. Stärz1, T. Windisch3, O. Grulke3, T. Klinger3, V. Naulin4, J. Juul Rasmussen4

1Institute for Ion Physics and Applied Physics, Association EURATOM-ÖAW, University of Innsbruck, Austria 2Association EURATOM/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico,

Av. Rovisco Pais, P-1049-001 Lisboa, Portugal 3Association EURATOM/RISØ-Technical University of Denmark, Roskilde, Denmark

4Max Planck Institute for Plasma Physics, EURATOM Association, Greifswald, Germany

Workshop topic: 11, Probe applications in fusion-oriented devices

Emissive probes offer the possibility for direct measurements of the plasma potential. In general the floating potential of an emissive probe presents an acceptable measure of the plasma potential. This method also works if there are electron drifts and beams in the plasma.

A conventional emissive probe consists of a loop of refractory wire such as tungsten, heated electrically by an external power supply or battery. An array of several probes was re-cently used in the edge plasma region of the Instituto Superior Técnico TOKamak (ISTTOK) [1], consisting of four heatable wire probes and one cylindrical probe staggered above each other with a distance of 2 mm between two adjacent probes. For comparison these probes were used as emissive probes and – by not heating them – as cold probes. The cylindrical probe was biased to ion saturation. The signals were mainly used to derive the radial turbulent flux. The probe manipulator was mounted at the low field side mid-plane of ISTTOK and could be moved radially.

We have also developed emissive probes consisting of just a pin of graphite or LaB6 of 1,5 mm diameter and 3 mm length, heated by a focused infrared laser beam of 808 nm wave-length delivered by a diode laser with a maximum output power of 50 W [2]. The last type of laser-heated probe can be shifted radially. The laser light is coupled to an optical fibre cable. The emerging beam from it is transformed into a parallel beam by a lens mounted on a quartz window of the VINETA machine at IPP Greifswald. Inside the vacuum chamber the parallel laser beam is focused by a lens with a focal length of 10 cm onto the probe pin. The probe pin, carried by a ceramic tube, and the lens are mounted on a radially movable system so that the focus always stays on the probe pin. In this way the probe can be shifted through more than one half of the VINETA plasma column without perturbation of the plasma by the lens, and the LaB6 pin can be heated to more than 1800°C. In the VINETA plasma we could produce an emission current of more than 2 A, which makes it suitable for even denser and hotter plasmas.

References

[1] R. Schrittwieser, C. Ionita, P. Balan, C. Silva, H. Figueiredo, C.A.F. Varandas, J. Juul Rasmussen, V Naulin, Plasma Phys. Contr. Fus. 50 (2008) 055004.

[2] R. Schrittwieser, C. Ionita, P. Balan, R. Gstrein, O. Grulke, T. Windisch, C. Brandt, T. Klinger, R. Madani, G. Amarandei, A. Sarma, Rev. Sci. Instrum. 79 (2008), 083508.

Corresponding author address

Codrina Ionita-Schrittwieser Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstr. 25, A-6020 Innsbruck, Austria e-mail: [email protected], phone: +43 512 507 6244

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Floating potentials in two-electron temperature plasma with two species of positive ions: theory and experiment

Milan Čerček1,2,4, Tomaž Gyergyek1,3,4 and Gregor Filipič1

1Jožef Stefan Institute, 1000 Ljubljana, Slovenia

2Faculty of Civil Engineering, University of Maribor, 2000 Maribor, Slovenia 3Faculty of Electrical Engineering, University of Ljubljana, 1000 Ljubljana, Slovenia

4Association EURATOM/MHEST

Workshop topic: 7, sheath and pre-sheath physics

Plasmas with two positive ion species are subject of intensive studies in recent years, both theoretically and experimentally [1, 2]. The knowledge of pre-sheath and sheath potential formation is of great importance, especially when ion flux from plasma and ion impact energy at the boundary surfaces is considered. Such issues are encountered in plasma devices for technological applications and also in edge regions of fusion machines. In this contribution we present the study on potential formation near a floating collector in discharge plasma with two ion populations and with a truncated bi-Maxwellian electron distribution. It is performed analytically with complementary computer simulations and some of the results, the floating potential dependence on various plasma parameters in particular, compared with experimental measurements. In the analytical study we use a fully kinetic plasma sheath model, originally developed by Schwager and Birdsall [3] and later extended in order to include additional particle species like hot electrons [4] and/or negative ions. In this particular case two positive ion populations are injected from the Maxwellian plasma source into the plasma system with an accelerated half-Maxwellian distribution, and the electron population is modelled with a truncated bi-Maxwellian distribution. The latter is typical for discharge plasma in which the hot electron population is formed from the electrons emitted from the hot cathode and accelerated into the system. The collector floating potential and the pre-sheath potential are calculated as functions of positive ion density fraction.

At the simulation experiment we use XPDP1 particle-in-cell simulation code for a bounded plasma system composed at Berkeley University. The potential and particle density profiles are examined and resulting particle velocity distribution functions along the system calculated and displayed. Good agreement with analytical results is obtained.

Experimental measurements are performed in a linear magnetized plasma machine in which the plasma column is on one side bounded by the hot cathode plasma source and on the other side by a floating collector. Floating potentials are measured at different plasma conditions determined by probe and ion acoustic phase velocity measurements. References [1] R.N. Franklin, J. Phys. D: Appl. Phys. 34 (2001), 1959. [2] D. Lee, N. Hershkowitz, G.D. Severn: Appl. Phys. Lett. 91 (2007), 041505. [3] L.A. Schwager, C.K.Birdsall, Phys. Fluids B 2 (1990), 1057. [4] M. Čerček, T. Gyergyek, J. Phys. D: Appl. Phys. 34 (2001), 330. Corresponding author address Milan Čerček Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia [email protected]

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Interpretation of Langmuir probe measurements during ELMs

D. Tskhakaya*

Association EURATOM-ÖAW, A-6020 Innsbruck, Austria *Permanent address: Andronikashvili Institute of Physics, 0177 Tbilisi, Georgia

Workshop topic: 7. Sheath and pre-sheath physics

Understanding of ELM generation mechanism and transport is one of the critical topics in magnetic confinement fusion research [1]. In recent years number of efforts has been made to model ELM transport in the SOL. These models reproduce quantitatively most of the ex-perimental observations, but not the Langmuir probe measurements. The problem is that the electron temperature in the ELMy divertor plasma, obtained from Langmuir probe measure-ments, never exceeds few tens on eV [2-6]. Contrary to this, the fluid (e.g. [5]) as well as ki-netic (e.g. [4, 7, 8]) models show temperatures as high as few hundreds of eV.

According to recent study the parallel propagation of the ELM in the SOL can be well described by collisionless transport of ELM particles having the pedestal temperature (Tped) [7-9]. Moreover, the propagation speed of the ELM front is well described by the sound speed with T=Tped. All these observations indicate that the probe measurements probably underesti-mate the electron temperature in the ELMy SOL.

In the present work we present the results of numerical modeling of probe measure-ments in the ELMy SOL and explain the reason of the mentioned disagreement between ex-periment and modelling. For simulations we use a PIC/MC code BIT1 code. The electron temperature is obtained directly from the electron velocity distribution (“real” temperature) as well as from “probe measurements” (“measured” temperature). In the pre-ELM SOL the real and measured temperatures agree well, while in the ELMy SOL the measured one is signifi-cantly lower. The reason of this disagreement is the strong deviation of ELMy electron veloc-ity distribution from the Maxwellian. We hope that the obtained results can be used for better interpreting of probe measurements in the ELMy SOLs.

References

[1] A. Loarte, et al., Phys. Scripta, T123 (2007), 222. [2] S. Jachmich, et al, Europ. Conf. Abstr. , 25A (2001), 1617. [3] A. Herrmann, et al, J. Nucl. Mater., 313–316 (2003), 759. [4] R.A. Pitts, et al, Nucl. Fusion, 43 (2003), 1145. [5] A Kallenbach,et al., Plasma Phys. Control. Fusion, 46 (2004), 431. [6] R.A. Pitts, et al, Nucl. Fusion, 47 (2007), 1145. [7] D. Tskhakaya, et al, Europ. Conf. Abstr. , 31F (2007), O2.002. [8] T. Eich, et al, J. Nucl. Mater., 390-391 (2009), 760. [9] D. Tskhakaya, et al, J. Nucl. Mater., 390-391 (2009), 335.

Corresponding author address

David Tskhakaya University of Innsbruck Technikerstrasse 25/II, A-6020 Innsbruck , Austria [email protected]

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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Numerical matching of the sheath and plasma solutions for a spherical probe in low-density plasma

Alif Din1, Siegbert Kuhn2 1,2Association EURATOM-ÖAW, Institute for Theoretical Physics,

Innsbruck University Technikerstraße 25, A-6020 Innsbruck

Workshop topic: 7, Sheath and pre-sheath physics

Finding the optimum matching between the (space-charge dominated) sheath solu-tion and the (quasineutral) plasma solution is quite a challenging problem. We have devel-oped a numerical procedure for finding the optimum matching point (i.e., radius) rmatch, which we define as the point where both the values and the derivatives of the two solutions coincide.

We start out from a fairly general spherical-probe scenario based on trajectory inte-gration of the Vlasov equation, which is then specialized to the particular situation considered by I. B. Bernstein and I. Rabinowitz [1], in which the incident ions are monoenergetic and isotropic. Using our own formalism, we have first reconstructed the “inward” sheath solution (r < r0, region without reflected ions), also found by B&R, but as a new result we have also found the “outward” sheath solution (r > r0, region with reflected ions). In this context we had to develop the above-mentioned numerical procedure for determining rmatch, which at the same time yields the correct value of r0, thus enabling correct integration of Poisson’s equa-tion for the inward and outward sheath solutions.

References

[1] Ira B. Bernstein and Irving Rabinowitz, Theory of electrostatic probes in low density plasma, Phys. Fluids 2(2) (1959), 112

Corresponding Author Address

Siegbert Kuhn Theoretical for Physics, University of Innsbruck Technikerstrasse 25, A-6020 Innsbruck, Austria [email protected] (+43-512) 507-6206

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

Notes

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International Workshop “50 Years Plasma Physics in Innsbruck” (IW50YPPI), September 24-25, 2009, Innsbruck, Austria

Foreword In the year 1958, Prof. Ferdinand Cap, at that time head of the Institute for Theoretical Phys-

ics of the University of Innsbruck, started to engage himself and his collaborators in theoretical plasma physics. This was the birth date of the Innsbruck Plasma Physics and Fusion Research. At first Profes-sor Cap treated mainly theoretical problems of magnetohydrodynamics and space plasmas, ten years later he also founded the Innsbruck Plasma Physics Laboratory, with the additional support of the Aus-trian Academy of Science and the American Government. These activities were an essential part of the so-called "Forschungsschwerpunkt Plasmaphysik" (Centre of Excellency in Plasma Physics) of the Austrian Science Funds, which was created at the end of the 1960's in Innsbruck. This Centre of Ex-cellency was extended several times until the 1980's.

For the "Forschungsschwerpunkt Plasmaphysik" Prof. Cap attracted further collaborators: Prof. Maximilian Pahl (died 1992), then head of the Institute for Atomic Physics (as it was called at that time), Prof. Josef Kolb (died 1994), then head of the Institute for Experimental Physics, and Prof. Rudolf Albrecht, then head of the Institute for Computer Science. The Innsbruck Plasma Laboratory had its home in the Institute for Atomic Physics, which later was renamed Institute for Ion Physics. Three years ago the institute was merged with another institute of the University of Innsbruck and is now called the Institute for Ion Physics and Applied Physics.

Since the late 1950's numerous scientists have studied and taught plasma physics in Inns-bruck and have occupied themselves with investigations of fascinating plasma physical effects. They have contributed to a better understanding of many phenomena and brought forth many masters and PhDs. Thank to Professor Cap's international experience a special feature of the Innsbruck Plasma Physics Community was its strong relations with other plasma physics groups world-wide from the very beginning. This was at a time when the international cooperation of Austrian Universities was anything but as common as it is today. So already in the 1960's and 1970's plasma physicists from the USA, India and Japan came to Innsbruck, staying here for several months or even years and contribut-ing essentially to our research. In the 1970's very important scientific contacts were established with Romania and Denmark, which also led to deep friendships. Plasma physicists from Innsbruck went abroad as well for long-term scientific visits. In the meantime also the EURATOM Association Pro-gramme and academic exchange networks extended the list of institutes collaborating with the Inns-bruck Plasma Physics Community over the whole of Europe.

To celebrate the fiftieth anniversary of the foundation of the Innsbruck Plasma Physics and Fusion Research, many friends and colleagues took part in a celebration at the University of Innsbruck on the 5th of December, 2008.

The current workshop is taking place to further commemorate this event. We have invited several of our long-term collaborators, who have since become dear friends, were invited to give talks on scientific subjects of common interest.

I would like to take this opportunity to thank all speakers who took it upon themselves to travel to Innsbruck and celebrate with us.

The invited speakers are asked to prepare up to 10-page manuscripts according to the style requirements of Contribution to Plasma Physics. After a formal reviewing process the manuscripts will be published in the same issue of Contribution to Plasma Physics as the contributions to the IEWP2009.

Roman Schrittwieser, Innsbruck, September 2009

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The Innsbruck Q-machine The hollow cathode The Innsbruck DP-machine

ISTTOK, Lisbon COMPASS, Prague

VINETA, Greifswald

ASDEX Upgrade, Garching JET, Culham

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Programme of the

International Workshop "50 Years Plasma Physics in Innsbruck"

Ground floor of Victor-Franz-Hess-Haus, Technikerstr. 25, Innsbruck, Auditorium (Hörsaal – HS) G and Foyer in front of it

Timing: 25 min presentation + 5 min discussion.

Thursday, September 24th

08:45 – 09:00 Opening Ceremony

09:00 - 10:30 1. Ferdinand Cap, The application of the Crocco theorem of neutral gasdynamics on plasmas p. 108

2. Padma Kant Shukla, Fundamentals of dusty plasma physics: An Interdisciplinary Research Field p. 110

3. Gheorghe Popa, A short history of Innsbruck – Iaşi col-laboration in scientific research p. 112

10:30 – 11:00 Coffee Break

11:00 – 12:00 1. Rikizo Hatakeyama, Collisionless drift waves ranging from current-driven, shear-modified, and electron-temperature-gradient modes p. 114

2. Jens Juul Rasmussen, The Q-machine: the plasma for waves and instabilities p. 116

12:00 – 13:30 Lunch

13:30 – 15:00 1. Milan Čerček, On the use of electron emitting probes in magnetized discharge plasma p. 118

2. Volker Naulin, On the role of blobs and holes in edge plasma p. 120

3. Victor Ciupina, Synthesis and characterization of some carbon-based nanostructures p. 122

15:00 – 15:30 Coffee Break

15:30 – 16:30 1. Reiner Stenzel, Contributions to fireball research in Innsbruck p. 124

2. Dan Gheorghe Dimitriu, Nonlinear effects related to the simultaneous excitation of three low-frequency insta-bilities in magnetized plasma p. 126

16:30 – 17:30 Closing Ceremony and Slide Show (once upon a time …)

18:00 – 19:00 Guided "hiking tour" (easy walk on a little upward slope) to the famous Buzihütte

19:00 - ….. Dinner Party in Buzihütte

Whenever Return on your own

Friday, September 25th

09:00 – 12:00 Discussions, Laboratory tours (upon arrangement with the organiz-ers)

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Abstracts of the

International Workshop "50 Years Plasma Physics in Innsbruck"

September 24 – 25, 2009, Innsbruck University

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The Application of the Crocco Theorem of Neutral Gasdynamics on Plasmas

Ferdinand Cap

Institute for Theoretical Physics, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria

The Crocco and the Vazsonyi theorems of neutral gases connect the flow vorticity with an entropy increase. For instance, the vorticity may be due to viscosity which in its turn increases entropy.

The extension of the Crocco theorem on plasmas leads to new insights. This exten-sion has been done in the Innsbruck doctoral thesis by Raimund Hommel. Since a plasma ex-hibits electric conductivity and other properties, the energy theorem must be rewritten. As a consequence the plasma state equation depends also on entropy.

Other consequences will also be discussed.

Corresponding author address

Ferdinand Cap Institute for Theoretical Physics, University of Innsbruck Technikerstr. 25, A-6020 Innsbruck, Austria e-mail: [email protected]

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VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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Fundamentals of Dusty Plasma Physics: An Interdisciplinary Research Field

Padma Kant Shukla

SUPA, Department of Physics, University of Strathclyde, Glasgow, Scotland, UK;

and Faculty of Physics & Astronomy, Ruhr University Bochum, Bochum, Germany

Mixtures of small charged particles (dust) with free electrons and ions (plasma) are found not in low-temperature laboratory discharges and in microelectronics, but also in inter-stellar space, in planetary systems, in cometary tails and comae, and in the near Earth envi-ronment (e.g. the polar mesosphere). Such multi-species dusty plasma systems are referred to as the plasma state of soft matter. Dusty plasmas have several remarkable features: First, there is a new dynamical variable of the dust grain charge which fluctuates; second, dynamical time scales associated with the motion of charged dust particles are stretched in terms of tens of milliseconds, yet the dust particles themselves can be easily visualized individually at a ki-netic level; third, there are new forces that attract charged dust particles of similar polarity; fourth, dusty plasmas exhibit the formation of dust Coulomb lattices and the phenomena of the phase transition and critical point depending on the Coulomb coupling parameter and in-ter-dust grain spacing. Hence, the field of dusty plasma physics is truly interdisciplinary, since it shares the knowledge with statistical physics and condensed matter physics.

In this talk, I shall highlight some of the basic and new physics which dusty plasmas enable us to study. Specifically, we shall describe the various dusty plasma environments, discuss the properties of dusty plasmas, as well as focus on dust grain charging, inter-dust grain forces, the various collective phenomena (e.g. the dust acoustic wave and its excitation), ordered dust structures (e.g. dust Coulomb crystals), and localized excitations (e.g. dust ion-acoustic shocks, dust acoustic Mach cones, dust voids and dust vortices, etc.) that are found. Finally, we briefly discuss application-oriented research (e.g, dusty plasma assisted charged carbon nanotubes) and the relevance of our investigation to nanotechnolgy and microgravity experiments on board the International Space Station (ISS).

Corresponding author address

Padma Kant Shukla SUPA, Department of Physics, University of Strathclyde, Glasgow, Scotland, UK; and Faculty of Physics & Astronomy, Ruhr University Bochum, Bochum, Germany e-mail: [email protected]

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VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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A short history of the Innsbruck–Iaşi collaboration in scientific research

Gheorghe Popa

Faculty of Physics, Al. I. Cuza University, 11 Carol I Blvd., 700506-Iasi, Romania

35 years ago research on waves and instabilities in the collisionless plasma of the Innsbruck Q-machine was initiated by Professor Ferdinand Cap based in the framework of international collaborations. New characteristics of the so-called ion-acoustic instability were presented showing the behaviour of an ion-acoustic standing wave [1] which raised new questions as: i) upstream and downstream propagation of the ion-acoustic wave, ii) ion-acoustic wave reflec-tion [2,3], iii) mechanism of instability and iv) their quenching [4-7]. These questions opened new topic of research later investigated also in these collaborations. Also the ion space charge instabilities was for the first time identified and studied in a single ended Q-machine [8,9], and later found also in the plasma of the Innsbruck DP-machine demonstrating the universal behaviour of plasma bounded by a bipolar potential structure [10].

The two dimensional spatial structure of the potential and its relaxation behaviour was also identified and studied in front of a positively biased button axially inserted into the Q-machine plasma column. It was shown that this relaxation process corresponds to so called electrostatic ion-cyclotron instability [11,12].

New and detailed results were obtained on the dynamics of a plasma double layer bounding the plasma structure formed in front of a positively biased electrode placed within an almost collisionless plasma of a multipolar confinement system [13]. Experiments are un-der investigation using fast camera recording of the DL dynamic [14] and LIF technique as one of the most powerful techniques present used in plasma diagnostic [15]. References 1. N. Sato, G. Popa, E. Märk, E. Mravlag, R. Schrittwieser, Phys. of Fluids 19 (1976), 70. 2. G. Popa, M. Oertl, Phys. Lett. 98A (1983), 110. 3. M. Oertl, G. Popa, Plasma Phys. Contr. Fusion 30 (1988), 529. 4. G. Popa, R.Schrittwieser, Phys. Lett. 75A (1980), 285. 5. G. Popa, R. Schrittwieser, E. Märk, Phys. Lett. 75A (1980), 288. 6. G. Popa, M. Sanduloviciu, S. Kuhn, M. Oertl, R. Schrittwieser, Phys. Lett. 87A (1982), 175. 7. M. Sanduloviciu, G. Popa, M. Oertl, Plasma Phys. Contr. Fusion 26 (1984), 472. 8. G. Popa, N. Sato, E. Märk, R. Schrittwieser, E. Mravlag, Phys. Lett. 53A (1975), 427. 9. G. Popa, N. Sato, E. Märk, R. Schrittwieser, E. Mravlag, J. Phys. D: Appl. Phys. 9 (1976), 397. 10. G. Popa, R. Schrittwieser, Phys. Plasmas 1 (1994), 32. 11. G. Popa, R. Schrittwieser, J.J. Rasmussen, P. Krumm, Plasma Phys. Contr. Fusion 27 (1985), 1063. 12. G. Popa, R. Schrittwieser, E. Mravlag, Plasma Phys. Contr. Fusion 31 (1989), 1863. 13. V. Pohoaţă, G. Popa, R. Schrittwieser, C. Ioniţă, M. Čerček, Phys. Rev. E 68 (2003), 16405. 14. L. de Poucques, C. Viţelaru, T.M. Minea, J. Bretagne, G. Popa, Europ. Phys. Lett. 82 (2008), 15002. 15. R. Cazan, G. Borcia, A. Chiper, G. Popa, Plasma Sources Sci. Technol. 17 (2008), 035020.

Corresponding author address: Gheorghe Popa Alexandru Ioan Cuza University B-dul Carol I, No. 11, RO-700506, Iaşi, Romania e-mail: [email protected] phone: +40 (232) 201025

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VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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Collisionless Drift Waves Ranging from Current-Driven, Shear-Modified, and Electron-Temperature-Gradient Modes

Rikizo Hatakeyama and Toshiro Kaneko

Department of Electronic Engineering, Tohoku University, Sendai 980-8579, Japan

Drift waves have attracted long-winded interest to plasma physicists from the dawn of plasma research activity spanning 50 years since Geneva Conference in 1958, which are considered to be universally destabilized by cross-field pressure gradients inherently existing in any kind of magnetized plasmas and a limiting factor to confinement of thermonuclear fu-sion plasmas. In the 1970’s, effects of magnetic-field-aligned electron currents on plasma in-stabilities were one of the topics. In the late 1977, low-frequency collisonless drift waves were started to be intensively investigated using the single-ended Q machine of University of Innsbruck [1], which are destabilized in the presence of both radial density gradients and elec-tron currents parallel to magnetic-field lines. For a smaller electron drift velocity, the meas-ured dispersion relations of the wave were found to be consistent with the linear theory of the current-driven collisionless drift instability. The temperature of the ions was observed to in-crease anisotropically concomitant with the growth of the drift wave [2].

Then in the late 1990’s and very early 2000’s, effects of flow velocity shears on plasma instabilities came out as important issue relating to both space and fusion-oriented plasma physics. Shear-modified collisionless drift waves have been studied in the Q machine of Tohoku University, which installs concentrically three-segmented electron and ion emitters at axial machine ends [3]. It is found that, broadly speaking, the velocity shears of magnetic-field aligned ion flows (parallel shear) and azimuthally rotated plasma flows (perpendicular shear) destabilize and stabilize the collisionless drift waves, respectively. In more detail relat-ing to the parallel shear, the collisionless drift wave is observed to be destabilized by a mag-netic-field- aligned ion flow velocity shear in the absence of field-aligned electron drift flow, but the instability is found to be gradually stabilized when the shear strength exceeds a critical value. The destabilizing and stabilizing mechanisms are well explained by a plasma kinetic theory including the effect of radial density gradient. A part of this work has been carried out as an international collaboration research with West Virginia University [4].

In recent years, anomalous electron transport in magnetically confined fusion-oriented plasmas is an important topic, where an electron temperature gradient (ETG) has been proposed to be one of the plausible candidates for its cause. Although there are some earlier studies on the ETG driven mode, these are related to toroidal plasmas and it is difficult to form the controllable ETG and clarify the relation between the plasma parameters and ETG mode. Thus, a basic experiment on the ETG mode is necessary. Here, we form and control the ETG in basic plasmas produced by a modified Q machine and observe low-frequency fluctua-tions induced by the ETG [5], which are associated with a collisionless drift instability. References [1] R. Hatakeyama, M. Oertl, E. Märk, R. Schrittwieser, Phys. Fluids 23 (1980), 1774. [2] R. Hatakeyama, M. Oertl, E. Märk, J. Phys. Soc. Jpn. 49 (1980), 845. [3] T. Kaneko, H. Tsunoyama, R. Hatakeyama, Phys. Rev. Lett. 90 (2003), 125001. [4] T. Kaneko, E.W. Reynolds, R. Hatakeyama, M.E. Koepke, Phys. Plasmas 12 (2005), 102106. [5] C. Moon, S. Tamura, T. Kaneko, R. Hatakeyama, to be published in Bull. Am. Phys. Soc. (2009). Corresponding author address: Rikizo Hatakeyama Department of Electronic Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan e-mail: [email protected], phone: +81-22-795-7045

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VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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The Q-machine: the plasma for waves and instabilities

Jens Juul Rasmussen

Risø National Laboratory for Sustainable Energy, Technical University of Denmark, PLF-128. P.O. Box 49, 4000 Roskilde, Denmark

Workshop topic: IW50YPPI

In the Q-machine plasma ions are produced by surface ionisation of alkaline metallic vapour on a hot plate, while the electrons are thermionically emitted from the same plate. The plasma is fully ionized and the cylindrical plasma column is radially confined by a strong ax-ial magnetic field. The plasma has a very low background noise level and the “Q” refers to Quiescent. This makes the Q-machine a very versatile device and well suited for performing fundamental investigations of waves and instabilities in magnetized plasma. The first Q-machine was constructed in 1960 in Princeton by Rynn and D’Angelo [1], and during the six-ties and seventies similar devices were built in many plasma laboratories around the world.

In this contribution I will discuss personally selected high-lights from the long list of invaluable contributions to basic plasma physics that have emerged from Q-machine research. This includes investigations of current driven instabilities as the ion cyclotron instability and ion acoustic instability, investigations of various nonlinear effects on wave propagation and plasma double layers.

[1] N. Rynn and N. D’Angelo Rev. Sci. Instrum. 31, 1326 (1960)

Corresponding author address

Jens Juul Rasmussen Risø DTU, PLF-128 Frederiksborgvej 399, DK-4000 Roskilde [email protected]. +45 4677 4537

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VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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On the Use of Electron Emitting Probes in Magnetized Discharge Plasma

Milan Čerček1,2,4, Tomaž Gyergyek1,3,4 and Boris Fonda1

1Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia 2Faculty of Civil Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia

3Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, 1000 Ljubljana, Slovenia 4Association EURATOM/MHEST

Codrina Ionita and Roman Schrittwieser

Institute for Ion Physics and Applied Physics, University of Innsbruck, A-6020 Innsbruck, Austria Association EURATOM/ŐAW

Emissive probes are standard tools for plasma diagnostic [1]. They are used in various plasmas like in low temperature laboratory plasmas, in high and low pressure plasmas for technological applications and recently also successfully in highly magnetized plasmas in ex-perimental fusion-oriented devices [2]. Usually they are used for determining steady or time varying values of plasma potential and electric fields in the plasma [3,4], more seldom they are also used for measuring the electron temperature. The plasma potential can be determined from the probe characteristic in various ways. The most straightforward way is to determine it by measuring its saturated floating potential at high emission. At such high emissions the space charge of the emitted electrons can significantly influence the probe characteristic. One-dimensional fluid models of the current-voltage characteristic with space-charge effect taken into account have been developed for an emissive probe immersed in plasma with Maxwellian electrons [5] as well as in two electron temperature plasma [6]. The latter is readily found in laboratory devices as well as in experimental fusion-oriented machines.

In the contribution we will present results of the comparisons of the model characteris-tics with those obtained experimentally. Experimental measurements were performed in a lin-ear magnetized plasma machine in which the plasma column is on one side bounded by the hot cathode plasma source and on the other side by a floating collector. It was confirmed ex-perimentally that at higher working pressures the electron population in the plasma is Max-wellian and at lower pressures it is bi-Maxwellian. An additional cold Langmuir probe was used to investigate the eventual perturbation introduced into the magnetized plasma by the use of the emissive probe. References [1] N. Hershkowitz in: O.Auciello, D.L.Flamm, Plasma Diagnostics Vol. 1, Academic Press, London, 1989. [2] R. Schrittwieser et al., Plasma Phys Contr. Fusion, 44 (2002) 567. [3] P. Balan, R. Schrittwieser, C. Ioniţă et al., Rev. Sci. Instrum., 74 (2003) 1583. [4] T. Gyergyek, M. Čerček, R. Schrittwieser, C. Ioniţă, G. Popa, V. Pohoaţa , Contrib. Pl. Phys.,43 (2003) 11. [5] M.Y. Ye, S. Takamura, Physics of Plasmas, 7 (200) 3457. [6] T. Gyergyek, M. Čerček, Eur. Phys. J. D, 42 (2007) 441. Corresponding author address Milan Čerček Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia [email protected]

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Notes

VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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On the role of blobs and holes in edge plasma

Volker Naulin1, Jens Juul Rasmussen1, Guosheng Xu2, Nicolla Vianello3 R. Schrittwieser4, C. Maszl4, C. Ionita4, F. Mehlmann4

1Association EURATOM/RISØ-Technical University of Denmark, Roskilde, Denmark 2Euratom-UKAEA, Culham Science Centre, Abingdon, OX14 3DB, UK and Institute of Plasma Physics, Chinese

Academy of Sciences, Hefei 230031,People’s Republic of China 3Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova, Italy

4Association EURATOM/ÖAW, Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

The occurrence of coherent structures in plasmas is an old topic and has ever since fascinated both physicists and laymen. Vortical structures have been analytically predicted as steady state or moving solutions to some of the paradigmatic plasma turbulence equations [1]. However, for long times these structures were thought to either play a limited role or to be-have nicely in the context of traditional transport modelling.

With the advent of fast cameras, blobs were found to be ubiquitous in plasmas, spe-cifically in the open magnetic field line region. The numerical simulation of these structures has been rather successful [2], and it is now widely accepted that the intermittent nature of cross field plasma transport due to these structures demands adjustments in the philosophy of the transport models we are using, even in the prediction towards machines like ITER.

Blob creation is however associated with the creation of holes as well [3]. While blobs can be readily observed, the experimental evidence for holes is sparse. Here we will ar-gue for certain situations under which holes and their propagation can be become important for the dynamics of the edge plasma.

References

[1] A. Hasegawa and K. Mima, Phys. Fluids 21 (1978), 87-92. [2] O.E. Garcia et al., Phys. Plasmas 12 (2005), 062309. [3] G. Xu et al., Nucl. Fusion 49 (2009), 092002.

Corresponding author address

Volker Naulin Risø DTU OPL 129 Frederiksborgvej 399, 4000 Roskilde, Denmark e-mail: [email protected], phone: +45 4677 4538

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Notes

VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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Synthesis and Characterization of Some Carbon-Based Nanostructures

V. Ciupina1, I. Morjan2, R. Alexandrescu2, F. Dumitrache2, G. Prodan1, C.P. Lungu2, R. Vladoiu1, I. Mustata2, V. Zarovschi2, J. Sullivan3, S. Saied3, E. Vasile4, I.M. Oancea-

Stanescu1, M. Prodan1, D. Manole1, A. Mandes1, V. Dinca1, M. Contulov1

1University of Constanta, Mamaia Avenue 124, Constanta, 900527, ROMANIA 2National Institute for Laser Plasma and Radiation Physics, Magurele, 077125, Romania

3Surface Science Group, School of Engineering and Applied Science, Aston University, Birmingham B4 7ET, UK

4Metav-CD S.A., Bucharest, 050025, Romania

Carbon-based nanostructures are of considerable interest for applications in nanotech-nologies related fields such as medicine, electronics, catalysis, environment, glasses etc. Typical carbon-based nanostructures methodologies involving different routes are presented: thin films vapour deposition procedures, iron-carbon nanostructures laser pyrolysis, catalyzed iron carbon nanoparticles, nanotubes, etc. The carbon thin films have been obtained by Thermionic Vacuum Arc method. The almost spherical carbon encapsulated iron nanoparti-cles with narrow size distribution were prepared via laser co-pyrolysis method in which the CW CO2-laser beam irradiates a gas mixture containing iron pentacarbonyl (vapours) and ethylene/acetylene hydrocarbons. Specific flow geometries were used in order to synthesize iron particle first followed by stimulate hydrocarbon decomposition at iron surface. High-resolution transmission electron microscopy images reveal the core-shell feature of synthe-sized nanostructures with around 2 nm thick carbon layers and 3-7 nm diameters iron-based core dimensions. The mean diameter could be experimentally controlled. A decreasing trend was found of particle size with the decreasing of pressure and total reactant gas flow. EELS, EDAX and Raman spectroscopy analysis confirm the simultaneous presence of carbon and iron. The nanoparticles were seeded onto Si wafer and further used as substrates for laser in-duced CVD carbon nanotubes growth. Depending on laser power density, nanotubes or nano-fibers are formed, in strong dependence on the location of iron based nanoparticles on Si sub-strates as revealed by SEM analysis. TEM, SAED, SEM, HRTEM, EELS, EDAX and Raman spectroscopy procedures have been used in order to characterize such carbon based nanostruc-tures.

Corresponding author address

Victor Ciupina University of Constanta, Mamaia Avenue 124, RO-900527 Constanta, ROMANIA e-mail: [email protected]

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Notes

VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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Contributions to Fireball Research in Innsbruck

Reiner Stenzel

Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547, USA

There is a long tradition of research on double layers and fireballs in Innsbruck. This talk will describe some recent results from two sabbatical visits at the Institute. Fireballs are discharge phenomena on anodes or positive electrodes in plasmas. A luminous plasma cloud is formed well outside the anode sheath by a double layer which accelerates electrons and ion-izes neutral gas. Fireballs assume many shapes and have intriguing properties. They are highly nonlinear phenomena covering the physics of sheaths, double layers, ionization, cath-odes, electrodes and various instabilities.

Double layers accelerate electrons into the fireball and ions out of the fireball. Stable fireballs require momentum balance between the opposing particle streams. When this is not satisfied fireballs grow and collapse. The properties of such relaxation instabilities will be ex-plained. Sheaths can also become unstable. The anode sheath can oscillate near the electron plasma frequency due to electron inertia. Sheath plasma instabilities have been observed and used for diagnosing sheath properties.

Fireballs in magnetic fields are particularly intriguing. Electrons are confined to move along field lines such that fireballs assume cylindrical or conical shapes. Unmagnetized ions are ejected across weak fields while magnetized electrons perform E×B drifts across field lines, another source for instabilities. In nonuniform magnetic fields like mirrors or cusps fireballs can become highly asymmetric.

Fireballs can be weak or powerful discharge phenomena depending on the electron source. They can exist even without cathodes in afterglow plasmas. Sputtering in discharges creates powerful fireballs. The anode properties can also influence fireball properties. On solid electrodes fireballs form on one side, on transparent grids they may form on both sides. They may cover the entire electrode or a portion of it. Many phenomena still await an expla-nation.

Fireballs have not yet found many applications but have potential for ion beam sources, processing plasmas. Thus, it remains an interesting research field to pursue.

Corresponding author address

Reiner Stenzel Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547, USA e-mail: [email protected] phone: 1 310 825 7898

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Notes

VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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Nonlinear Effects Related to the Simultaneous Excitation of Three Low-Frequency Instabilities in Magnetized Plasma

D.G. Dimitriu1, C. Ionita2, R. W. Schrittwieser2

1Faculty of Physics, Alexandru-Ioan-Cuza University of Iasi, Romania 2Institute for Ion Physics and Applied Physics, Leopold-Franzens University of Innsbruck, Austria

Experimental results are reported on nonlinear effects related to the simultaneous exci-tation of three low-frequency instabilities in the edge region of the magnetized plasma column of a Q-machine: the potential relaxation instability, the electrostatic ion-cyclotron instability and the Kelvin-Helmholtz instability. The potential relaxation instability and the electrostatic ion-cyclotron instability are excited by drawing an electron current parallel to the magnetic field to a circular collector. For exciting the potential relaxation instability, the radius of the collector has to be sufficiently larger than the ion gyroradius, so that the ion trajectories can be considered as one-dimensional. For exciting the electrostatic ion-cyclotron instability, the radius of the collector must be considerably smaller than that of the plasma column, but still in the range of a few ion gyroradii. A certain range of collector radii where both instabilities could be excited simultaneously was found. The Kelvin-Helmholtz instability appears in the edge region of a rotating plasma column, where a shear of the azimuthal flow exists. To ob-tain all three instabilities simultaneously, a circular collector with a certain diameter was placed in the edge region of a Q-machine plasma column and positively biased with respect to the plasma potential. The instabilities are identified in the power spectrum of the oscillations of the current to the collector. The static current-voltage characteristic of the collector reveals the existence of certain current jumps and hysteresis cycles associated with the appearance of the instabilities. For low values of the magnetic field and high values of the potential applied to the electrode, the development of the Kelvin-Helmholtz instability leads to the suppression of the potential relaxation instability and a strong decrease in the coherence of the electro-static ion-cyclotron instability. By increasing the magnetic field, first the coherence degree of the electrostatic ion-cyclotron instability increases, while the Kelvin-Helmholtz instability is suppressed and the potential relaxation instability re-appears. At high values of the magnetic field the coherence of the electrostatic ion-cyclotron instability decreases again, with the peak of the potential relaxation instability remaining dominant in the power spectrum of the current oscillations. For certain values of the plasma parameters, a strong interaction between the po-tential relaxation instability and electrostatic ion-cyclotron instability was observed, leading to amplitude and frequency modulation of the latter by the former.

Corresponding author address

Dan Gheorghe Dimitriu Faculty of Physics Alexandru-Ioan-Cuza University Iasi, Romania Telephone: +40-757-039815 e-mail: [email protected]

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Notes

VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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List of participants

Name Surname Affiliation Address Remarks

Jiři Adámek Institute of Plasma Phys-ics, Czech Academy of Science, Prague, Czech Republic

Za Slovankou 3, 18200 Prague, Czech Republic, [email protected]

IWEP2009 & IW50YPPI

Alexandra Avram Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

Secretary of the Local Organizing Committee (LOC)

Jun Gyo Bak National Fusion Re-search Institute, Yusung-Gu, Daejeon, Korea

113 Gwahangno, Yusung-Gu, 305-333, Daejeon, Korea, [email protected]

IWEP2009

Ferdinand Cap Institute for Theoretical Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

IW50YPPI, Invited Speaker

Milan Čerček Jožef Stefan Institute, Ljubljana, Slovenia

Jamova cesta 39, SI-1000 Ljubljana, Slovenia, [email protected]

IWEP2009 & IW50YPPI, Invited Speaker International Scientific Committee (ISC)

Victor Ciupina Ovidius University of Constanta, Romania

B-dul Mamaia 124, RO-900527 Con-stanta, Romania c/o [email protected]

IW50YPPI, Invited Speaker

Luis Conde Dpto. Fisica Aplicada, ETSI Aeronauticos, U.P.M Madrid, Spain

Cardenal Cisneros 3, E-28040 Madrid, Spain [email protected]

IWEP2009 &IW50YPPI

Gianluca De Masi Consorzio RFX, Assoc. EURATOM-ENEA, Pa-dova, Italy

C.so Stati Uniti 4, I-35127 Padova, Italy, [email protected]

IWEP2009

Vladimir Demidov Physics Department, West Virginia Univer-sity, Morgantown, WV, USA

Morgantown, WV 26506, USA, [email protected]

IWEP2009

Dan Dimitriu Faculty of Physics, Al-exandru-Ioan-Cuza Uni-versity, Iaşi, Romania

B-dul Carol I 11, RO-700506 Iaşi, Romania, [email protected]

IW50YPPI, Invited Speaker

Jose Manuel Donoso Dpto. Fisica Aplicada, ETSI Aeronauticos, U.P.M Madrid, Spain

Cardenal Cisneros 3, E-28040 Madrid, Spain, [email protected]

IWEP2009 & IW50YPPI

VIII IWEP & IW50YPPI

VIII IWEP 2009 Innsbruck 8th International Workshop on Electric Probes in Magnetized Plasmas & International Workshop “50 Years Plasma Physics in Innsbruck” 21/09 – 25/09/2009 Innsbruck, Austria Institute for Ion Physics and Applied Physics, University of Innsbruck

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Naomichi Ezumi Nagano National Col-lege of Technology, Na-gano, Japan

716 Tokuma, 381-8550, Nagano, Ja-pan, [email protected]

IWEP2009

Felix Gennrich Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

IWEP2009

Valery Godyak RF Plasma Consulting, Brookline, MA, USA

1265 Beacon Stress, #402, Brookline, MA 02446, USA [email protected]

IWEP2009 & IW50YPPI

Etalina Godyak Accompanying person with V. God-yak!

Gurusharan Singh

Gogna Dublin City University, Dublin, Ireland

47 Christfield Avenue, Dublin 9, Ire-land, [email protected]

IWEP2009 & IW50YPPI

Johannes Grünwald Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

LOC

Jamie Gunn Institut de recherches sur la fusion magnétique, CEA Cadarache, France

IRFM Bât. 508, F-13108 St Paul Lez Durance, France, [email protected]

IWEP2009

Tomaž Gyergyek Faculty of electrical en-gineering, University of Ljubljana, Slovenia

Tržaška 25, SI-1000 Ljubljana, Slo-venia, [email protected]

IWEP2009 & IW50YPPI

Mario Hannemann Institut für Niedertem-peratur plasma, Greifswald, Germany

Felix-Hausdorff-Straße 2, D-17489 Greifswald, Germany, [email protected]

IWEP2009 & IW50YPPI

Rikizo Hatakeyama Tohoku University, Sendai, Japan

6-6-05 Aza-Aoba, Aramaki, Aoba-ku , 980-8579 Sendai, Japan, [email protected]

IWEP2009 & IW50YPPI, Invited Speaker

Patrick Hofreiter Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

Codrina Ioniţă-Schrittwieser

Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

IWEP2009 & IW50YPPI LOC

Shantanu Karkari National Centre for Plasma Science and Technology, Dublin, Ire-land

Collins Avenue, Dublin 9, Ireland [email protected]

IWEP2009 & IW50YPPI

Jan Klusoň Faculty of Mathematics and Physics, Charles University in Prague Czech Republic

V Holešovičkách 2, CZ-18000 Pra-gue, Czech Republic, [email protected]

IWEP2009

Martin Kocan Institut de recherches sur la fusion magnétique, CEA, Cadarache, France

IRFM Bât. 508, F-13108 St Paul Lez Durance, France, [email protected]

IWEP2009

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Michael Komm Institute of Plasma Phys-ics, Czech Academy of Science, Prague, Czech Republic

Za Slovankou 3, 18200 Prague, Czech Republic, [email protected]

IWEP2009 & IW50YPPI

Jaroslav Kousal Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic

V Holešovičkách 2, CZ-18000 Pra-gue, Czech Republic, [email protected]

IWEP2009

Pavel Kudrna Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic

V Holešovičkách 2, CZ-18000 Pra-gue, Czech Republic, [email protected]

IWEP2009

Siegbert Kuhn Institute for Theoretical Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

IWEP2009 & IW50YPPI

Naomi Kurahara Kyushu Institute of Technology, Kitakyu-shu, Japan

1-1 Sensui-cho, Tobata-ku, 804-8550, Kitakyushu, Japan, [email protected]

IWEP2009

Michael Laux MPI für Plasmaphysik, Teilinstitut Greifswald, Germany

Wendelsteinstrasse 1, D-17491 Greifswald, Germany, [email protected]

IWEP2009 Chairman ISC

Stefan Marsen MPI für Plasmaphysik, Greifswald, Germany

Wendelsteinstrasse 1, D-17491 Greifswald, Germany, [email protected]

IWEP2009

Emilio Martines Consorzio RFX, Padova, Italy

corso Stati Uniti 4, I-35127 Padova, Italy [email protected]

IWEP2009 & IW50YPPI ISC

Christian Maszl Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

IWEP2009 & IW50YPPI LOC

Franz Mehlmann Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

IWEP2009 & IW50YPPI LOC

Lekha Nath Mishra Faculty of Science, Uni-versity of Tromsø, Nor-way

N-9037 Tromsø, Norway, [email protected]

IWEP2009 & IW50YPPI

Hans Werner Müller MPI für Plasmaphysik, Garching bei München, Germany

Boltzmannstr. 2, D-85749 Garching, Germany, [email protected]

IWEP2009 ISC

Volker Naulin Risø National Labora-tory, Technical Univer-sity of Denmark

Frederiksborgvej 399, P.O. Box 49 DK-4000 Roskilde, Denmark, [email protected]

IW50YPPI, Invited Speaker

Igor Nedzelskiy Instituto de Plasma e Fusao Nuclear, Lisbon, Portugal

Rovisco Pais, P-1049-001 Lisbon, Portugal, [email protected]

IWEP2009

Gheorghe Popa Faculty of Physics, Al-exandru-Ioan-Cuza Uni-versity, Iaşi, Romania

B-dul Carol I, no. 11, RO-700506 Iaşi, Romania [email protected]

IWEP2009 & IW50YPPI, Invited Speaker ISC

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Tsviatko Popov Faculty of Physics, St. Kliment Ohridski Uni-versity of Sofia, Bul-garia

5, James Bourchier BLVD, BG-1164 Sofia, Bulgaria, [email protected]

IWEP2009 & IW50YPPI, ISC

Jens Juul Rasmussen Risø National Labora-tory, Technical Univer-sity of Denmark

Frederiksborgvej 399, P.O. Box 49 DK-4000 Roskilde, Denmark, [email protected]

IW50YPPI, Invited Speaker ISC

Abdur Razzak Faculty of Engineering, Aichi Institute of Tech-nology, Toyota, Japan

1247 Yachigusa, Yakusa-cho, 470-0392, Toyota, Japan, [email protected]

IWEP2009

Sakila Halima Accompanying person with A. Raz-zak!

Celso Ribeiro Faculty of Science and Technology, New Uni-versity of Lisbon, Portu-gal

Quinta da Torre, Caparica, P-2829-516 Almada, Portugal, [email protected]

IWEP2009

Seiki Saito Faculty of Engineering, Aichi Institute of Tech-nology, Toyota, Japan

13-83-522, 507-0814, Ichinokura, Tajimi, 470-0392 Toyota, Japan, [email protected]

IWEP2009

Arun Sarma School of Petroleum Technology, Pandit Deendayal Petroleum University, Gandhina-gar, India

Raisan Village, 382008, Gandhinagar, India, [email protected]

IWEP2009

Roman Schrittwieser Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

IWEP2009 & IW50YPPI Chairman LOC

Padma Shukla Department of Physics- University of Strath-clyde, Glasgow, Scot-land, U.K and Faculty of Physics and Astronomy, Ruhr University, Bo-chum, Germany

Gebäude7/23, D-44780 Bochum, Germany [email protected]

IW50YPPI, Invited Speaker

Marius Solomon Faculty of Physics, Al-exandru-Ioan-Cuza Uni-versity, Iasi, Romania

B-dul Carol I, no. 11, RO-700506 Iaşi, Romania [email protected]

IWEP2009 & IW50YPPI

David Speirs Department of Physics, University of Strath-clyde, Glasgow, Scot-land, U.K.

107 Rottenrow street, G4 0NG, Glas-gow, UK [email protected]

IWEP2009

Ronald Stärz Institute for Ion Physics and Applied Physics, University of Innsbruck

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

IWEP2009 & IW50YPPI

Reiner Stenzel Department of Physics and Astronomy, UCLA, Los Angeles, USA

Los Angeles, CA 90095, USA [email protected]

IWEP2009 & IW50YPPI, Invited Speaker ISC

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Jan Stöckel Institute of Plasma Phys-ics, Czech Academy of Science, Prague, Czech Republic

Za Slovankou 3, 18200 Prague, Czech Republic, [email protected]

IWEP2009 ISC

Tomonori Suzuki Graduate School of Sci-ence, Tohoku Univer-sity, Sendai, Japan

6-3 Aramaki-Aza-Aoba, Aoba-ku, 980-8578, Sendai, Japan, [email protected]

IWEP2009

Milan Tichý Faculty of Mathematics and Physics, Charles University in Prague, Czech Republic

V Holešovičkách 2, CZ-18000 Pra-gue, Czech Republic, [email protected]

IWEP2009

Wouter Tierens Department of Applied Physics, Ghent Univer-sity, Gent, Belgium

Wiemersdreef 20, BE-9000 Gent, Belgium, [email protected]

IWEP2009

Kano Todoroki Nagano National Col-lege of Technology, Na-gano, Japan

716 Tokuma, 381-8550, Nagano, Ja-pan, [email protected]

IWEP2009

Yukihiro Tomita National Institute for Fusion Science, Toki, Japan

322-6 Oroshi-cho, 509-5292, Toki, Japan, [email protected]

IWEP2009 & IW50YPPI

Oliver Troll Dpto. Fisica Aplicada, ETSI Aeronauticos, U.P.M Madrid, Spain

Cardenal Cisneros 3, E-28040 Madrid, Spain [email protected]

IWEP2009

David Tskhakaya Institute for Theoretical Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

IWEP2009 & IW50YPPI LOC

Kazuya Uehara Japan Atomic Energy Agency, Naka Fusion Establishment, Naka-City, Japan

Mukoumama/801-1, 311-0193, Naka-city, Japan, [email protected]

IWEP2009

Patrick Winkler Institute for Ion Physics and Applied Physics, University of Innsbruck, Austria

Technikerstr. 25, A-6020 Innsbruck, Austria, [email protected]

IWEP2009 & IW50YPPI

Minyou Ye MPI für Plasmaphysik, Teilinstitut Greifswald, Germany

Wendelsteinstrasse 1, D-17491 Greifswald, Germany, [email protected]

IWEP2009 & IW50YPPI

Guangwu Zhong Southwestern Institute of Physics, Chengdu, P. R. China

No.3, 3rd Section, South of 2nd Ring Road, 610041, Chengdu, China [email protected]

IWEP2009 & IW50YPPI

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Author Index

A Abe T.....................................................40 Adámek J...................................28, 64, 66 Adams S.F. ...........................................26 Al R.S. ...................................................84 Alexandrescu R. .................................122 Amemiya H. ..........................................56 Andrew P...............................................42 Anita V. .................................................84

B Bak J.-G.................................................82 Biedermann H........................................74 Blessington J. .......................................26 Boilson D...............................................88

C Cap F. .................................................108 Cavazzana R. ...................................46, 68 Čechvala J. ............................................74 Čerček M. .....................................96, 118 Chichina M. ..........................................76 Cho M. ..................................................38 Ciupina V. ...........................................122 Conde L. ..........................................32, 34 Contulov M. ........................................122 Costin C.................................................84 Criado E.................................................32

D De Masi G. ............................................46 Dejarnac R. ...........................................90 Demidov V.I. ........................................26 Dimitriu D.G. ......................................122 Dimitrova M..........................................30 Din A. ..................................................100 Dinca V. ..............................................122 Donoso J.M. ....................................32, 34 Duarte P. ...............................................70 Dumitrache F. .....................................122

E Ezumi N. .........................................54, 86

F Feng Y. .................................................86 Fernandes H. .........................................70 Figueiredo H....................................70, 94 Filipič G.................................................96 Fonda B. ..............................................118 Frederiksen Å. ......................................50

G Gauthier E. ............................................58 Gennrich F. ...........................................48 Godyak V.A. .........................................36

Gogna G.S. ............................................ 88 Gopi S. ................................................. 18 Greuner H.............................................. 52 Grulke O. .............................................. 94 Gunn J.M......................................... 44, 58 Gyergyek T. .................................. 96, 118

H Hannemann M. ..................................... 24 Hatakeyama R. ............................. 22, 114 Herdrich G............................................. 32 Horaček J......................................... 64, 66 Hubička Z. ............................................ 78

I Innocente P............................................ 46 Ionita C................ 64, 66, 68, 94, 118, 120 Ivanova P. ............................................. 90

J Jian G. .................................................. 42

K Kaneko T. ..................................... 22, 114 Karkari S.K. .......................................... 88 Kawamura G. ........................................ 62 Kendl A. ................................................ 48 Kim J.Y. ................................................ 82 Klinger T. ............................................. 94 Klusoň J. ......................................... 76, 78 Kobayashi M. ....................................... 86 Kobayashi T. ........................................ 86 Kočan M. ........................................ 44, 58 Koepke M.E. ......................................... 26 Komm M. ....................................... 28, 60 Kousal J. ............................................... 74 Kudrna P. ....................................... 76, 78 Kuhn S................................................. 100 Kumamoto A. Kurahara N. ........................................... 38 Kurzan B. .............................................. 66

L Laube R. ............................................... 52 Laux M.................................................. 52 Lee S.G.................................................. 82 Leshkov S.............................................. 76 Lindig S................................................. 52 Lopes-Cardozo N.J................................ 84 Lorenzini R............................................ 46 Lungu C.P. .......................................... 122 Lupu C................................................... 68

M Mandes A. ........................................... 122 Manole D............................................. 122 Maraschek M......................................... 68

133

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Marsen S. ...............................................20 Martines E. ............................................46 Masuzaki S. ..........................................86 Maszl C....................................68, 94, 120 Mehlmann F.................48, 64, 66, 68, 120 Mihaila I. ...............................................84 Mishra L.N.............................................50 Momo B.................................................46 Morjan I. ..............................................122 Müller H.W................................64, 66, 68 Munaretto S. ..........................................46 Mustata I. ............................................122

N Nagashima Y. ........................................56 Naulin V. .................................68, 94, 120 Nedzelskiy I.S........................................70

O Oancea-Stanescu I.M...........................122 Ohno N. ................................................86 Ono T.....................................................40 Otte M....................................................20

P Panek R. ................................................28 Pascal J.-Y. ...........................................58 Patel A. .................................................18 Peer J. ...................................................48 Pekarek Z. .............................................28 Picková I. ........................................76, 78 Pitcher C.S. ............................................42 Popa G. ..........................................84, 112 Popov Tsv.K. ..................................30, 90 Prodan G. ............................................122 Prodan M. ...........................................122

R Rapp J. ...................................................84 Rasmussen J.J. .................68, 94, 116, 120 Razzak M.A. ..........................................72 Ribeiro C. ..............................................92 Rohde V.....................................64, 66, 68

S Sadamoto Y. ..........................................56 Saied S. ...............................................122 Saito S. ............................................72, 80 Sakamoto M...........................................56 Sarma A.K. ............................................18 Sawada K. .............................................86 Schrittwieser R. ...48, 66, 68, 94, 118, 120 Šebek O. ...............................................74 Serianni G. .............................................46 Shukla P.K. ..........................................110 Silva C. ............................................70, 94 Simonin A..............................................88 Solomon M.L. .......................................84 Spagnolo S.............................................46 Spolaore M. ...........................................46

Stärz R. .................................................94 Steffen F. ..............................................20 Stenzel R. .............................................16 Stöckel J. ...................................60, 66, 90 Sullivan J. ...........................................122 Suzuki T. ...............................................40

T Takamura S......................................72, 80 Talukder M.R. ......................................80 Tang Y...................................................42 Terranova D...........................................46 Tichý M. ...................................74, 76, 78 Tierens W. .............................................60 Todoroki K. .....................................54, 86 Tomita Y. ..............................................62 Troll O. ..................................................32 Tskhakaya D..........................................98 Turner M.M. ..........................................88

U Uehara K. ..............................................56 Uemoto J. ..............................................40 Urrutria J.M. .........................................16

V Van der Meiden H.J...............................84 Van der Pool M. ....................................84 Van Oost G. ..........................................60 Van Rooij G.J. .......................................84 Vasile E. ..............................................122 Vianello N. ..............................46, 68, 120 Vladoiu R. ...........................................122

W Wagner F. .............................................20 Weinzettl V............................................66 Williamson J.M. ....................................26 Windisch T. ...........................................94

X Xu G. ...................................................120

Y Yang Q. .................................................42 Ye M.Y..................................................52

Z Zarovschi V. ........................................122 Zhong G.................................................42 Zuin M. ...........................................46, 68

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Page 138: Book of Abstracts - uibk.ac.at · ported that "radiant matter" and gases have ... The contributions to IWEP2009 in this Book of Abstracts have been ... Electron energy distribution

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