1. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT PWI activities at CIEMAT (Madrid) presented by F. Tabarés Laboratorio Nacional de Fusión por Confinamiento Magnético Asociación EURATOM/CIEMAT. Madrid.Spain EU-PWITF. Ljubljana 13-15 Nov. 2006

2. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT OUTLINE -Wall conditioning of TJ-II -Carbon erosion studies in TJ-II - Particle transport studies in TJ-II - Removal/inhibition of carbon co-deposits -Scavengers: Laboratory studies JET experiments -Oxidation, plasma assisted techniques -Wall conditioning of TJ-II -Carbon erosion studies in TJ-II - Particle transport studies in TJ-II - Removal/inhibition of carbon co-deposits -Scavengers: Laboratory studies JET experiments -Oxidation, plasma assisted techniques

3. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT Wall conditioning of TJ-II TJ-II Stellerator (R=1.5 m, a <0.23 m, B=1T) Boronisation at beginning of the exp. campaign 4 gr o-carborane in He GD B/C ~ 50nm He (Ne) GD 30 min at beginning of experimental day. ECRH plasmas (up 600 kW): good impurity control (Z~1) and acceptable density control. NBI plasmas (up 400 kW): uncontrolled increase of density We need a good H 2 and O 2 getter Lithium coating TJ-II Stellerator (R=1.5 m, a <0.23 m, B=1T) Boronisation at beginning of the exp. campaign 4 gr o-carborane in He GD B/C ~ 50nm He (Ne) GD 30 min at beginning of experimental day. ECRH plasmas (up 600 kW): good impurity control (Z~1) and acceptable density control. NBI plasmas (up 400 kW): uncontrolled increase of density We need a good H 2 and O 2 getter Lithium coating

4. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT First test of Lithium coating 4 Lithium ovens: 2 fixed (side windows) and 2 in retractable manipulators (top windows) 1 gr of Li per oven, heated to ~600 ºC during Ne GD Emission of Li injected from a retractable oven Emission of Li injected from a retractable oven

5. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT First test of Li coating Problems: -Lack of good temp. control in the inserted ovens: strong asymmetry of deposited Li. -Accidental venting of TJ-II with N 2. Production of Li 3 N ?? Results: ECRH plasmas (N plasmas?) with a poor density control. Very low H fuelling required Next campaign: 4 fixed oven. More lab. work in order to improve the coating: Li + He/Ne GD (simultaneous or consecutive) Problems: -Lack of good temp. control in the inserted ovens: strong asymmetry of deposited Li. -Accidental venting of TJ-II with N 2. Production of Li 3 N ?? Results: ECRH plasmas (N plasmas?) with a poor density control. Very low H fuelling required Next campaign: 4 fixed oven. More lab. work in order to improve the coating: Li + He/Ne GD (simultaneous or consecutive)

6. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT C-film formation and erosion in TJ-II CH 4 and C 2 H 4 have been injected at the plasma edge using a mobile, instrumented limiter, producing local C-films. Identical (reference ) limiter at 180 º(PSI-2006 to appear J. Nucl. Mat.) -C 2 H 4 presents much lower fuelling efficiency than H 2 -C 2 H 4 yields only a 15% of H /Hatom compared with H 2 -CH/H 3x higher in C 2 H 4 vs CH 4 -C 2 H 4 presents much lower fuelling efficiency than H 2 -C 2 H 4 yields only a 15% of H /Hatom compared with H 2 -CH/H 3x higher in C 2 H 4 vs CH 4 -C 2 H 4 injection produced C-layers with high H content (from particle balance) -No difference in erosion between methane/ethylene layers -Physical sputtering dominant -C 2 H 4 injection produced C-layers with high H content (from particle balance) -No difference in erosion between methane/ethylene layers -Physical sputtering dominant Results

7. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT

8. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT Erosion of local C-layers Comparison of erosion of the deposited films by plasmas fed by limiter puffing or by machine puffing Comparison of erosion of the deposited films by plasmas fed by limiter puffing or by machine puffing Global contamination of the full wall Global contamination of the full wall Higher erosion by plasmas feed away for the limiter Higher erosion by plasmas feed away for the limiter

9. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT Other studies in TJ-II Transport Studies Implementation of EIRENE code to the TJ-II geometry By J. Guasp & A. Salas. Applications: -Simulation of He ECRH plasma using He emission lines of 3 different. Neutral profiles obtained. (EPS-2006) -H profile modeling. (E. de la Cal PSI-2006). Diagnostics Testing of He C-R model by a supersonic He beam. Sensitivity of model to rate constant uncertainties Use of LIF for change population in collisional-coupled levels and estimate the rates of transition with n=0. (A. Hidalgo et al. PPCF 48 (2006) 527. Transport Studies Implementation of EIRENE code to the TJ-II geometry By J. Guasp & A. Salas. Applications: -Simulation of He ECRH plasma using He emission lines of 3 different. Neutral profiles obtained. (EPS-2006) -H profile modeling. (E. de la Cal PSI-2006). Diagnostics Testing of He C-R model by a supersonic He beam. Sensitivity of model to rate constant uncertainties Use of LIF for change population in collisional-coupled levels and estimate the rates of transition with n=0. (A. Hidalgo et al. PPCF 48 (2006) 527.

10. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT Modeling of He plasmas by EIRENE in TJ-II -EIRENE neutral code (2) adapted to TJ-II geometry: First case. - 9.6 M trajectories for neutral He followed. - Statistical uncertainty 3% in the He line ratios. - He line ratios insensitive to most of the model parameters. - He line ratios very sensitive to ne and Te edge profiles - Edge profiles adjusted, inside the experimental error limits, for the best fitting. The edge profiles from Thomson Scattering and He-beam in H plasmas are a starting point for the simulation Dotted lines: exp. error limits (20%) Continuous lines: statistical uncertainty of EIRENE (3%) Edge parameters: ne=1.09x10 12 cm -3, Te= 41 eV Good Fitting with smooth edge profiles Neutral profiles: Absolute calibration of 667 nm He line (error 50%) Adjust parameters: Ne(a) = 1.09x10 12 cm -3 ( 8%) Te(a) = 41 eV ( 4%) Ti(0) = 80 eV ( 24%) Ti(a) = 25 eV ( 10%) He + /He ++ = 90% ( 10%) p = 5.6 ms ( 20%)

11. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT Validation of the C-R model for He in a supersonic He beam in TJ-II Supersonic He beam diagnostic: Edge profile and Validation of C-R model -a) Comparison with reflectrometry, Li beam and TS--> density profile - b) Comparison with ECE Langmuir probes and TS--> temperture profile -c) Self consistency: reproduction of full emission radial profile emiss.(nm) 667 706 728

12. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT Removal Techniques Film scavengers: Complete suppression of C-film deposition in technical plasmas by addition of some reactive gases: N 2, NH 3, CNH, SH 2, etc… Suppression of C deposition in CH 4 /N 2 /H 2 (10:0-10:80) GD (PPCF 44 (2002) L37) N 2 injection on sub-divertor ASDEX-Up: suppression of C re-deposition (Nucl. Fusion 45 (2005) L27) N 2 sub-divertor injection tested in JET: Nov. 2006 Film scavengers: Complete suppression of C-film deposition in technical plasmas by addition of some reactive gases: N 2, NH 3, CNH, SH 2, etc… Suppression of C deposition in CH 4 /N 2 /H 2 (10:0-10:80) GD (PPCF 44 (2002) L37) N 2 injection on sub-divertor ASDEX-Up: suppression of C re-deposition (Nucl. Fusion 45 (2005) L27) N 2 sub-divertor injection tested in JET: Nov. 2006

13. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT Mechanism of C-film inhibition Cryogenic Trap Assisted Mass Spectrometry (CTAMS) 1-pumping system7-diaphragm 2-B-A manometer8-mass spectr. 3-Cap. Manometer9-optic port 4-cutting valve10-manipulator 5-gas inlet11-cryogenic trap 6-anode12-float V measure 1-pumping system7-diaphragm 2-B-A manometer8-mass spectr. 3-Cap. Manometer9-optic port 4-cutting valve10-manipulator 5-gas inlet11-cryogenic trap 6-anode12-float V measure Vapor pressure vs. T for different species Vapor pressure vs. T for different species J.A. Ferreira et al. PFMC-11. Griefswald 2006 21 IAEA. Chengdu 2006 Submitted: J.Vac.Sci.Tech. Chem Vap. Dep. J.A. Ferreira et al. PFMC-11. Griefswald 2006 21 IAEA. Chengdu 2006 Submitted: J.Vac.Sci.Tech. Chem Vap. Dep.

14. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT CTAMS results CH 4 /N 2 /H 2 (10:10:80) plasma N 2 /H 2 (20:80) plasma condensation release Main product: acetylene Main product: acetylene Main product: HCN Main product: HCN

15. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT CTAMS summary Proposed mechanism: Proposed mechanism:

16. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT JET experiments ( Nov.06) Three scenarios: - SP low Horizontal+ Type I ELMs,GIM 11, Q<1.2 10 22 e/s - SP low Horizontal-sweep + Lmode,GIM 11, Q< 6.10 21 e/s - SP low Vertical + Type I ELMs,GIM 11 Q<8 10 21 e/s N2N2 N2N2

17. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT JET experiments ctnd N2 in H mode L mode No significant effect seen with SP at low tile 3 either (H mode) Compatibility of toroidal injection with Type I ELM for required N 2 fluxes at JET??? try local injection with AUG fluxes(extrapolated)

18. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT Removal of a-C:H in gaps Plasma etching in castellated structures (1mm wide x3mm deep) Plasma etching in castellated structures (1mm wide x3mm deep) Etching rates Deduced by full annealing (TDS) before and after plasma exposure: He/O 2 (20%): 12 nm/min H 2 /N 2 (20%): 3.6 nm/min B/C films: much lower rates Etching rates Deduced by full annealing (TDS) before and after plasma exposure: He/O 2 (20%): 12 nm/min H 2 /N 2 (20%): 3.6 nm/min B/C films: much lower rates Similar rates if C-coated elements were facing the bottom of the chamber where only a weak plasma was detected (LP) Similar rates if C-coated elements were facing the bottom of the chamber where only a weak plasma was detected (LP) Atomic O, surviving after a few collisions with the walls, is the responsible of cleaning. Atomic O, surviving after a few collisions with the walls, is the responsible of cleaning. J.A. Ferreira et al. 12-ICFRM. Sta. Barbara. 2005 To appear in J. Nucl. Mater. J.A. Ferreira et al. 12-ICFRM. Sta. Barbara. 2005 To appear in J. Nucl. Mater.

19. Laboratorio Nacional de Fusión Asociación EURATOM-CIEMAT C-studies (future-2007) CD,C 2, He beam emission (pulsed) -Chemical sputtering of doped graphite (metal carbides) (in collaboration C. Garcia-Rosales) TJ-II NBI Plasma C doped C Methane/He injection Holder: rotable, radial displacement