1E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Deuterium retention in Tore Supra long...

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Transcript of 1E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Deuterium retention in Tore Supra long...

  • Slide 1
  • 1E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Deuterium retention in Tore Supra long discharges Interpreting the particle balance Particle retention during long discharges Particle recovery (after shot, glows, disruptions) Experimental results E. Tsitrone, C. Brosset, J. Bucalossi, B. Pgouri, T. Loarer, P. Roubin 2, Y. Corre, E. Dufour, A. Graud, C. Grisolia, A. Grosman, J. Gunn, J. Hogan 3, C. Lowry, R. Mitteau, V. Philips 4, D. Reiter 4, J. Roth 5, M. Rubel 6, R. Schneider 7, M. Warrier 7 Association Euratom-CEA, CEA Cadarache, CEA-DSM-DRFC, F-13108 Saint Paul-lez-Durance, France 2 : LPIIM, UMR 6633, Universit de Provence, Centre Saint-Jrme13 397 Marseille cedex 20 3 : Fusion Energy Division, ORNL, Oak Ridge, TN 37831-8072 USA 4 : Institut fr Plasmaphysik, FZ Jlich, Euratom Association, D-52425 Jlich, Germany 5 : Max Planck Institute fr Plasmaphysik, Euratom Association, Boltzmannstr. 2, D-85748 Garching Germany 6 : Alfven Laboratory, Royal Institute of Technology, Association Euratom VR, 100 44 Stockholm, Sweden 7 : Max Planck Institute fr Plasmaphysik, Euratom Association, Teilinst. Greifswald, Wendelsteinstrasse 1, D-17491 Greifswald Germany
  • Slide 2
  • 2E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Tore Supra : the CIEL configuration Long pulse : LH driven discharge at V loop ~ 0, low plasma current/density low density hot edge plasma (Te ~ 100 eV at the LCFS) Toroidal pump limiter (TPL) Bumpers Outboard movable limiter 15 m 2 of carbon plasma facing components Active cooling : stationary PFC temperature from 120C (cooling loop) up to 250C on the limiter for long pulses Plasma loaded zones Shadowed zones CCD imaging of the TPL Active pumping : neutralisers below TPL
  • Slide 3
  • 3E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Phase 1 Phase 2 Particle retention in long discharges No saturation of in vessel retention after 15 minutes of cumulated plasma time Phase 2 Constant retention rate (= 50% of injected flux) No saturation after 6 minutes Identical shot to shot behaviour Phase 1 (~ 100 s) Decreasing retention rate In vessel inventory shot duration in phase 2 (I max = 8 10 22 D for 6 minutes)
  • Slide 4
  • 4E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Phase 1 Phase 2 Retention phase 1 x 10 21 Particle recovery after shot Recovery > plasma content : the wall releases particles x 10 22 Recovery correlated to retention in phase 1 : transient retention mechanism Small fraction recovered after shot ~ 100 s
  • Slide 5
  • 5E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Particle recovery after glow discharge and disruptions Recovery after He glow discharge (6 hours) : 1.5 - 2 10 22 D < I max Independent of the quantity trapped during the day of experiment Recovery after disruption : up to 5 10 22 D < I max Large scatter at given Ip : machine history dependent ? (highest exhaust in start up phase) Threshold in Ip : Ip < 0.8 MA : ~ after shot recovery Ip > 0.8 MA : increase with Ip dissipated energy high enough to heat D rich deposited layers [D. Whyte, PSI 2004]
  • Slide 6
  • 6E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Sample analysis : D content Outboard limiter Cold deposits (~ 120 C) D/C ~ 10 % N D ~ 10 22 at /m 2 / m * S * d TPL Neutraliser finger Hot deposits (> 500C) D/C ~ 1 % N D ~ 10 21 at/m 2 * S [C. Brosset, PSI 2004] TPL deposits analysis still in progress Cold deposits in shadowed areas D reservoir Several ms Shadowed < 1 m Plasma facing Several ms Carbon deposits Net deposition zone Net erosion zone (main plasma interaction area) Net deposition zones
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  • 7E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Interpreting the particle balance BUT : does not explain shot to shot behaviour unless very strong diffusion takes place Phase 1 Progressive saturation of bombarded surfaces (D +, D 0 ) until C Dmax reached Implantation D C D +, D 0 d imp < 0.1 m Carbon D+D+ D0D0 D2+D2+ D2D2 TPL Bumpers [E. Tsitrone, PSI 2004] Saturation time : from ~ 1s (TPL) to ~ 100 s (bumpers)
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  • 8E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Phase 1 Interpreting the particle balance Outgassing after shot ~ phase 1 duration ( ~ 100s) : ok with filling / emptying the porosity reservoir Good candidate for phase 1 BUT : extrapolation from lab to tokamak environment (temperature) TS deposited layers : 100 times more porous than original CFC [P. Roubin, PSI 2004] Filling the CFC porosity D 2, D 0 Adsorption M. Warrier et al., Contrib. Plasma Phys. 44, No. 1-3, (2004) Adsorption : weak bond ( chemical bond) ok for transient mechanism Extrapolation from lab exp (77 K) : 10 22 D/g deposits 0.5 g enough to account for phase 1 5 10 21 D
  • Slide 9
  • 9E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Interpreting the particle balance Phase 1 + 2 ok with Zeff, ok with low net erosion on TPL (high local redeposition), ok with layers growing rate 10 20 C/s 1.5 10 20 CD 4 /s Distant redeposition (TPL shadowed areas, neutralisers, outboard limiter ) 6 10 20 C/s (phys. + self) 1.5 10 20 CD 4 /s (chem.) Erosion 5 10 20 C 6+ /s Local redeposition Preliminary estimates of carbon erosion sources physical + chemical sputtering by D + and D 0 self sputtering by C n+ (assumed 5% C in D + flux) Codeposition : Carbon deposits C, D CxDyCxDy physical sputtering chemical sputtering carbon balance roughly coherent
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  • 10E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Interpreting the particle balance Phase 1 + 2 If D/C = 0.1 : need 2 10 21 C/s of net redeposition : high erosion/redeposition on TPL ( > 100 m on 4 m 2 ): not observed No coherence between D retention rate / D/C ratio / C erosion/redeposition D rich film created during the discharge subsequently depleted in D (glows, disruptions) ? Hard to explain the retention rate in phase 2 with codeposition alone 1/3 of produced CD 4 trapped : but high D/C ratio film : not observed 2 10 20 D/s 10 20 C/s 1.5 10 20 CD 4 /s Distant redeposition (TPL shadowed areas, neutralisers, outboard limiter ) 6 10 20 C/s 1.5 10 20 CD 4 /s Erosion 5 10 20 C 6+ /s Local redeposition Codeposition : D balance
  • Slide 11
  • 11E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Summary Phase 2Phase 1 D implantation in C : progressive saturation but not transient D adsorption in porosity : good candidate, but to be assessed in tokamak environment Codeposition of D and C : Can hardly explain the retention rate in phase 2 D content sample analysis : D mainly in cold deposits in shadowed areas (120 C) Missing D not found yet but still a lot to investigate (TPL deposits, pumping ducts ) D recovery (He glow discharge, disruptions) < in vessel inventory accumulated in a single long discharge D retention : no wall saturation after 15 minutes in high T e / low n e edge plasma Transient retention : recovered after shot Permanent retention : NOT recovered after shot
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  • 12E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom
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  • 13E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Tore Supra : well equipped for particle balance Gas injection : manometers Active pumping : 10 neutralisers with turbo- molecular pumps equipped with 20 pressure gauges (1 in vertical port, 1 at the pump) + 2 Penning gauges (D 2 /He) + mass spectrometer 2 pressure gauges in the chamber (equatorial ports) pressure gauges in primary exhaust system Systematic calibration procedure : calibrated gas injection in the chamber with/without pumps activated D + to pumps dN p /dt = inj pump in vessel
  • Slide 14
  • 14E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Effect of active pumping Pumping on Active pumping on Tore Supra : no effect on dynamic wall retention but offset on gas injection Pumping off Same wall inventory Shifted gas injection
  • Slide 15
  • 15E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom LH power (MW) Injected flux (Pa.m 3 /s) Extracted Flux (Pa.m3/s) Gas Puffing Vessel Inventory TPL exhaust Vessel Exhaust Plasma Content x100 Inventories (Pa.m 3 ) s Time (s) Shot 32299 Particle balance sensitive to LH power loss dN p /dt = inj pump in vessel
  • Slide 16
  • 16E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Shot 33067 T (C) before/after disruption (20 ms) Disruption heats deposited layers Net erosion zone (main plasma interaction area) Thickest deposition zone (shadowed/plasma area) Moderate deposition zone (plasma interaction area) T > 220 C Plasma loaded zones Shadowed zones CCD imaging of the TPL
  • Slide 17
  • 17E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom TC #33067 (t-20ms) T #33067 (disruption) IR shows cold deposits
  • Slide 18
  • 18E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom D inventory in the machine Estimated D inventory in the machine : From analysed samples : ~ 5 10 22 D (80% in cold deposits) From non analysed samples (TPL surface) : ~ 4 10 22 D (most of it in TPL shadowed zones) Total : ~ 9 10 22 D Estimated D inventory from particle balance integrated over a campaign: From averaged net retention rates : ~ 1.5 10 24 D Glow discharge : ~ 4 10 23 D Disruptions : ~ 3 10 23 D Total : ~ 8 10 23 D No firm conclusion can be drawn on D balance BUT : surface/depth of layers difficult to assess, samples still to be analysed BUT : retention rate scenario dependent, not all disruptions recorded, glow D 2 not accounted, cleaning discharges
  • Slide 19
  • 19E. Tsitrone20th IAEA Vilamoura 1-6/11/2004 Euratom Deuterium ret