Status of Di vertor P lasma S imulator – II ( DiPS -II)

1CENTER for EDGE PLASMA

SCIENCES

CEPS

Status of Divertor Plasma Simulator – II (DiPS-II)

2nd PMIF Workshop

Sep. 19, 2011

Julich, Germany

H.-J. Woo1 , K.-S. Chung1, S.-J. Park1, S.-G. Cho1, E.-K. Park1, and T. Lho2

1Center for Edge Plasma Science, Hanyang University, Seoul 133-791, Korea2National Fusion Research Institute, Daejeon 305-333, Korea


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CEPSCONTENTS

• Review of DiPS – I

• LaB6 Cathode

• Concepts and Objects of DiPS – II

• Summary and Future Work


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CEPS

Units in mm

Divertor SimulatorSpace/Astrophysics Simulator

TMP (1000 l/s)

TMP (550 l/s)

355 178 1007 658 829TP (FSP)

189184

SP, MP (FSP), LIF(Measurement Position)

Detachable on Rail

SP

Laser Injection

LaB6 DCPlasma Source

Helicon RFPlasma Source

DiPS-I : Schematics

Magnet

LaB6 Cathode

LaB6 is located at null magnetic field.

DiPS - I


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CEPS Typical Magnetic Field of DiPS-I

DiPS - I


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CEPS

5

-35 -30 -25 -20 -15 -10 -5 0 5

0.0

0.1

0.2

0.3

0.4

-20 -18 -16 -14 -12 -10-10

-5

0

IDIS=10 A

IDIS=14 A

IDIS=18 A

Vp~2 V

I (Am

p.)

V (Volts)

IDIS= 22 A IDIS= 18 A IDIS= 14 A IDIS= 10 A

IDIS=22 A

Vf~2 V

-35 -30 -25 -20 -15 -10 -5 0

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

-20 -18 -16 -14 -12 -10-8

-6

-4

-2

0

2

BD=405 G

BD=332 G

BD=259 G

Vp~0.3 V

I (Am

p.)

V (Volts)

BD=186 G, Bmax=695 G BD=259 G, Bmax=705 G BD=332 G, Bmax=715 G BD=405 G, Bmax=724 G

BD=186 G

Vf~0.3 V

• Probe Diagnostics : I-V Characteristics

vs. Magnetic Field vs. Discharge Current

Dimensions of Probe Tip: 0.5 mm (Dia.) and 3 mm (length)

, , ,(B) (405 G) (185 G) 0.3 V p f p f p fV V V

, DIS , ,(I ) (22 A) (10 A) 2 V p f p f p fV V V

, (B) / 0.01p f DISV V

, DIS(I ) / 0.063p f DISV V

DiPS – I : Experimental Results


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CEPS

6

10 12 14 16 18 20 221.0

1.5

2.0

2.5

3.0

1

2

3

4

5

6

7

8

Elec

tron

Tem

pera

ture

(eV)

Discharge Current (A)

Te

np Plas

ma D

ensit

y (1012

cm-3 )

200 250 300 350 4001.0

1.5

2.0

2.5

3.0

1

2

3

4

5

6

7

8

Elec

tron

Tem

pera

ture

(eV)

Magnetic Field Intensity (G)

Te np

Pla

sma D

ensi

ty (1

012 cm

-3 )

• Probe Diagnostics : Electron Temperature (Te) and Plasma Density (np)

vs. Magnetic Field vs. Discharge Current

(B) 2.55 0.23 eVeT DIS(I ) 2.65 0.08 eVeT

Plasma Density : Confinement Effect Plasma Density : Particle Flux Density



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CEPS

7

0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60

0.080

0.085

0.090

0.095

0.100

0.105

0.110 Ti

Till

Ion

Tem

pera

ture

(eV)

BD/Bmax

0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60-50

0

50

200

250

300

Drift

Velo

city (

m/s)

BD/Bmax

vDll

vD

• LIF Diagnostics vs. Magnetic Field

Ion Temperature Drift Velocity

Ion temperature and parallel flow velocity are increased versus the magnetic field in-tensity.

The perpendicular flow velocity remains near zero, since the contributions of E X B and diamagnetic effect are negligible at the plasma center in the magnetized cylindri-

cal plasmas.



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CEPS

8

10 12 14 16 18 20 22

-50

0

50

100

150

200

250

300

350

400

Drift

Velo

city

(m/s

)


vD ll

vD

10 12 14 16 18 20 22

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

Ion

Tem

pera

ture

(eV)


Ti

Till

• LIF Diagnostics vs. Discharge Current

Ion Temperature Drift Velocity

Ion temperature and parallel flow velocity are increased versus the discharge cur-rent.



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CEPS

9

1 2 3 4 5 6 7 8

0.04

0.06

0.08

0.10

0.12

100

200

300

400

500

Ion

Tem

pera

ture

(eV)

Plasma Density (1012 cm-3)

Ti (Discharge Current) Till (Discharge Current) Ti (Magnetic Field) Till (Magnetic Field)

Flo

w Ve

locit

y (m

/s)

vDll (Discharge Current) vDll (Magnetic Field)

• Ion Temperature and Drift Velocity vs. Plasma Density

Magnetic Field Variation → Ion Temperature (Plasma Density + Magnetic Field) Discharge Current Variation → Ion Temperature (Plasma Density)



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CEPS LaB6 Cathode for DiPS – I & II

LaB6 Cathode for DiPS – I & II


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CEPS LaB6 Cathode for MP2 – Large Plasma Source

Outer LaB6Cathode Array

Inner LaB6Cathode

290 mm

Water CooledHeater Power Line

Copper Holder

Inner LaB6 Cathode(4 inch Dia.) x 1 ea

Outer LaB6 Cathode(2 inch Dia.) x 6 ea

Inner and OuterGraphite Heater

Stainless Steel Support

Graphite Holder

LaB6 Cathode for Large Plasma Generation


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CEPS

0 2 4 6 8 10 12 140.75

0.80

0.85

0.90

0.95

1.00

~450 oK

~370 oK

~1400 oK

R/R 0

Heating Power (kW)

Inner Heater of MP2

Outer Heater of MP2

Heater of DiPS~1600 oK

0 50 100 150 200 250 300 350 4000.050

0.055

0.060

0.065

0.070

0.080

0.085

0.090

0.095

0.100

0.105

0.110

R (

)

Heating Current (A)

Inner Heater Outer Heater

Heater Temperature Estimation

LaB6 Cathode : Heater Temperature Estimation


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B. Noyes, Jr., Phys. Rev. 24, 190 (1924).

Heater Temperature Estimation

LaB6 Cathode : Heater Temperature Estimation


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Objective of DiPS-II

• Understanding of the Plasma Wall Interaction• Higher Plasma Flow Generation with Magnetic Nozzle Concept. • Characterizations of Attached/Detached Plasmas (Neutral Effects).

– Need Highly Differential Pumping• Developments of Diagnostics for KSTAR. • Tests of PFC Materials.

DiPS - II

DiPS – II has been developed to overcome the weaknesses of DiPS – I and improve the machine performance.Weaknesses of DiPS – I:• Neutral Pressure Control – only two section separated by differential

pumping.• Low Particle Flux – limited plasma current.• Small Plasma Size : Core Plasma Size ~ 2 cm


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CEPSDiPS - II

B. Labambard, 21st Transport Taskforce Workshop, Boulder, CO (March 25-28, 2008) .


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CEPS Concepts of Magnetic Nozzle – From Helicon Experiments

X. Sun, Phys. Rev. Lett. 95, 025004 (2005)

HELIX and LEIA, West Virginia University

Helicon Plasma Without Ion Heating

VASIMR Concepts

DiPS - II


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CEPS

Heliconplasma

source willbe installed

FSPLaB6 Cathode

TMP 1600 l/sTMP 1600 l/s

TMP 1600 l/s

0 1 2 3 4 5 6

0

1

2

3

4

B (k

G)

Axial Distance (m)

M1 M2-M5 M6-M15M16-M17

M18-M19Source Region Central Cell Transient & Expansion Region

Measurement Position A & B

Concepts of Magnetic Nozzle – From Experience of MP2 (NFRI: Dr. LHO)

DiPS - II


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18

0 20 40 60 80 1000

1

2

3

4

5

Curre

nt R

atio

(Jup

/J dn)

Radial Profile (mm)

30 A 50 A 70 A 90 A

-10 0 10 20 30 40

2

4

6

8

Curre

nt R

atio

(Jup

/J dn)

Radial Position (mm)

30 A 50 A 70 A 90 A

High Field Chamber (Position A): Magnetized

1st Port of Central Cell (Position B): Un-magnetized


DiPS - II


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CEPS

19

0 20 40 60 80 1000.0

0.2

0.4

0.6

0.8

1.0

Mach

No.

(VD/C

S)Radial Position (mm)

30 A 50 A 70 A 90 A

0 10 20 30 400.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Mach

Num

ber

Radial Position (mm)

30 A 50 A 70 A 90 A


High Field Chamber (Position A): Magnetized

1st Port of Central Cell (Position B): Un-magnetized

DiPS - II


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CEPS Schematic Diagram of DiPS-II Magnetic Nozzle

DiPS - II


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CEPS Typical Magnetic Field of DiPS-II

Magnet Power Supply Magnet Label Default CurrentSorensen SGI 80- 125 M1 – M2 80 A (Max. 125 A)Sorensen SGI 80 - 125 M3 – M4 60 A (Max. 125 A)

Sorensen SGI 40 – 250 (Parallel) M5 – M6 450 A (Max. 500 A)Sorensen SGI 200 – 125 M7 – M12 5 – 90 A (Max. 125 A)

DiPS - II


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CEPS

Diagnostics and Material Test Regime

First Plasma at Sep. 2010.

DiPS - II

Construction and Plasma Generation


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CEPS LaB6 Cathode Damage (Melting) at High Current Operation (over 90 A)

In diverging field configuration, the LaB6 cathode can be damaged by localized current in light gas operation such as helium (low ion gyro-radius).

→ Need the Null Field Geometry

LaB6 Cathode Melting

DiPS - II


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CEPSDiPS – II : Flow Measurement Results

-10 -8 -6 -4 -2 0 2 4 6 8 10-3

-2

-1

0

1

2

3

4

5+

LIF

Inte

nsity

(arb

. uni

ts)

Frequency Shift (GHz)

-

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

The plasma flow velocity is nearly zero (stationary plasma), which might be due to grounded chamber wall disturbs the ion acceleration.


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CEPS Install Laser Thomson Scattering for Detached Plasmas & Material Test

Nd:YAG Laser(2nd harmonic: 532 nm)

CollectionOptics

Beam Dump

ICCD

Triple GratingMono-Chrometer

Plasma

Mirror Array

BrewsterWindow &

Baffle

BrewsterWindow &

Baffle

Injected Laser Beam

Scattered Light

Mirror & Lens Array

TS SampleHorizontal Pixel No. (related to Wavelength)

Vert

ical

Pix

el N

o. (r

elat

ed to

Rad

ial P

ositi

on)

R = 0 mmR = - 3.5 mm

R = +3.5 mm

R = -7 mm

R = +7 mm

R = +10.5 mmR = +14 mm

R = -14 mm

R = -10.5 mm

Blocked Region (Rayleigh Scattering)

DiPS – II: TS Diagnostics


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CEPSDiPS – II: TS Diagnostics

40 A Discharge with Ar


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CEPSTypical Di-

vertor DiPS-1 DiPS-2Pressure @ Source (m-Torr) 1 – 30 200 - 400 20 - 50

Pressure @ Transient (m-Torr) - 5

Pressure @ Diagnostics (mTorr) 1 - 30 1 - 10 0.1 – 100

Core Plasma Size ~2 cm ~ 5 cm

Plasma Density (cm-3) 1013 – 1014

<1014 @ near Source

~1012 @ diagnos-tics

~1013 @ Diagnos-tics

Electron Temperature (eV) 1-10 eV 2-3 eV for Ar,

5-7 eV for He2-3 eV for Ar, 5-7 eV for He

Ion Temperature Ti~Te 0.1 eV for Ar 0.1 eV for Ar

Particle Flux (m-2s-1) ~ 1024 ~1022 1022 - 1024

Magnetic Field ~ 3 T ~ 1 kG BT=3.5 kG, BD=1.5 kG max.

Discharge Voltage ~ 30 - 40 V for Ar~ 60 - 80 V for He

~ 50-70 V for Ar~100 V for He

Discharge Current 50 A DC 150 A DC

SUMMARY


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CEPSSUMMARY

DiPS-1 DiPS-2

PLASMA DIAG-NOSTICS PROBES PROBES

LASER-INDUCED FLUO-RESCENCE

LASER-INDUCED FLUO-RESCENCE

LASER THOMSON SCAT-TERING

ETCSmall Size Ion Beam Source

will be Installedfor Material Damage Test


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CEPS

• One will change magnetic nozzle chamber as floating structure (or biased structure), which is now grounding.

• One also add the source magnet for cusp magnetic field.• The design is already finished.

FUTURE WORK

Status of Di vertor P lasma S imulator – II ( DiPS -II)

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