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Study of negative ion surface production in caesium -free H 2 plasma PhD student : Kostiantyn Achkasov Tutors: Gilles

3 rd FUSENET PhD Event in Fusion Science and Engineering University of York , 23 rd - 26 th of July 2013 . Study of negative ion surface production in caesium -free H 2 plasma PhD student : Kostiantyn Achkasov Tutors: Gilles Cartry and Alain Simonin. Fundamentals.

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Study of negative ion surface production in caesium -free H 2 plasma PhD student : Kostiantyn Achkasov Tutors: Gilles

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  1. 3rd FUSENET PhD Event in Fusion Science and Engineering University of York, 23rd - 26thof July 2013 • Study of negative ion surface production in caesium-free H2plasma • PhD student: • Kostiantyn Achkasov • Tutors: • Gilles Cartry and Alain Simonin

  2. Fundamentals • Controlled thermonuclear fusion is one of the most promising future energy sources 3rd FUSENET PhD Event in York:26thof June 2013

  3. Fundamentals • Controlled thermonuclear fusion is one of the most promising future energy sources 3rd FUSENET PhD Event in York:26thof June 2013

  4. Fundamentals • Controlled thermonuclear fusion is one of the most promising future energy sources • ITER is the world's largest experimental tokamak nuclear fusion reactor being built at the south of France 3rd FUSENET PhD Event in York:26thof June 2013

  5. Fundamentals • Controlled thermonuclear fusion is one of the most promising future energy sources • ITER is the world's largest experimental tokamak nuclear fusion reactor being built at the south of France • Requiredelectrontemperature: 10 – 20 keV (~108 °C) • only1 keVcanbeachievedwithOhmicheating 3rd FUSENET PhD Event in York:26thof June 2013

  6. Fundamentals • Controlled thermonuclear fusion is one of the most promising future energy sources • ITER is the world's largest experimental tokamak nuclear fusion reactor being built at the south of France • Requiredelectrontemperature: 10 – 20 keV(~108 °C) • only1 keVcanbeachievedwithOhmicheating one needs additional heating methods! 3rd FUSENET PhD Event in York:26thof June 2013

  7. NBI for ITER NBI - neutral beam injection 3rd FUSENET PhD Event in York:26thof June 2013

  8. NBI for ITER NBI - neutral beam injection Total weight > 900 tons Bushing 17 MW & 1 MeV of neutrals 5.3 m Calorimeter RID Neutralizer Ion source and accelerator 4.7 m 15 m 3rd FUSENET PhD Event in York:26thof June 2013

  9. Why to use i- ? neutrals of 1 MeV are needed to heat the ITER plasma core and ignite the fusion reactions 3rd FUSENET PhD Event in York:26thof June 2013

  10. Why to use i- ? Ion neutralization neutrals of 1 MeV are needed to heat the ITER plasma core and ignite the fusion reactions At such an energy: D+→ 0% D-→ 56% of neutralisation efficiency 3rd FUSENET PhD Event in York:26thof June 2013

  11. Why to use i- ? Ion neutralization neutrals of 1 MeV are needed to heat the ITER plasma core and ignite the fusion reactions At such an energy: D+→ 0% D-→ 56% of neutralisation efficiency NecessaryD- current: ~ 50 A (250 A∙m-2) 3rd FUSENET PhD Event in York:26thof June 2013

  12. Why to use i- ? Ion neutralization neutrals of 1 MeV are needed to heat the ITER plasma core and ignite the fusion reactions At such an energy: D+→ 0% D-→ 56% of neutralisation efficiency NecessaryD- current: ~50 A (250 A∙m-2) new large i- source has to be developed! 3rd FUSENET PhD Event in York:26thof June 2013

  13. Present i– source i- source concept RF Driver 13 3rd FUSENET PhD Event in York:26thof June 2013

  14. Present i– source i- source concept RF Driver • i- surface production • with Cs deposition • has many drawbacks like diffusion of Cs inside the accelerator • is presently the only way to meet ITER requirements 14 3rd FUSENET PhD Event in York:26thof June 2013

  15. Present i– source i- source concept RF Driver • i- surface production • with Cs deposition • has many drawbacks like diffusion of Cs inside the accelerator • is presently the only way to meet ITER requirements Alternative solutions to the use of Cs would be highly valuable for the future fusion i- sources! 15 3rd FUSENET PhD Event in York:26thof June 2013

  16. Experimental set-up Pyrex tube • HeliconreactorPHISIS • H2 and D2 plasma • P = 20 – 900 W • no magneticfield • preactor = 0.2 – 2 Pa • capacitivelycoupled plasma mode Antenna Coils Mass Spectrometer Hiden EQP 300 Pump Graphite sample 16 3rd FUSENET PhD Event in York:26thof June 2013

  17. Experimental set-up • HeliconreactorPHISIS • H2 and D2 plasma • P = 20 – 900 W • no magneticfield • preactor = 0.2 – 2 Pa • capacitivelycoupled plasma mode 17 3rd FUSENET PhD Event in York:26thof June 2013

  18. Sample Langmuir probe Experimental set-up Mass Spectrometer 18 3rd FUSENET PhD Event in York:26thof June 2013

  19. Measurement principle Mass Spectrometer Sample Plasma Vs VMS Vp 0 E 19 3rd FUSENET PhD Event in York:26thof June 2013

  20. Measurement principle Mass Spectrometer Sample Plasma Vs VMS Vp 0 E Negative ion distribution function (NIDF) 20 3rd FUSENET PhD Event in York:26thof June 2013

  21. Modeling of the NIDF 21 3rd FUSENET PhD Event in York:26thof June 2013

  22. Modeling of the NIDF SRIM: the stopping and range of ions in matter 22 3rd FUSENET PhD Event in York:26thof June 2013

  23. NIDF of i- emitted by the surface × × Plasma transmission Modeling of the NIDF Surface Mass spectrometer transmission 23 3rd FUSENET PhD Event in York:26thof June 2013

  24. NIDF of i- emitted by the surface × × Plasma transmission Modeling of the NIDF Surface Mass spectrometer transmission SRIM 24 3rd FUSENET PhD Event in York:26thof June 2013

  25. NIDF of i- emitted by the surface × × Plasma transmission Modeling of the NIDF Surface Mass spectrometer transmission SRIM SIMION 25 3rd FUSENET PhD Event in York:26thof June 2013

  26. Modeling of the NIDF • good agreement between F’’(E) and Fmeasured(E) 26 3rd FUSENET PhD Event in York:26thof June 2013

  27. Modeling of the NIDF • good agreement between F’’(E) and Fmeasured(E) • SRIM calculation: C-H layer with30% of hydrogen on the surface 27 3rd FUSENET PhD Event in York:26thof June 2013

  28. NIDF study of different carbon materials • highly oriented pyrolitic graphite (HOPG) 28 3rd FUSENET PhD Event in York:26thof June 2013

  29. NIDF study of different carbon materials • highly oriented pyrolitic graphite (HOPG) 29 3rd FUSENET PhD Event in York:26thof June 2013

  30. NIDF study of different carbon materials • highly oriented pyrolitic graphite (HOPG) F”(E,θ) 30% H 30 3rd FUSENET PhD Event in York:26thof June 2013

  31. NIDF study of different carbon materials • highly oriented pyrolitic graphite (HOPG) F”(E,θ) 30% H 31 3rd FUSENET PhD Event in York:26thof June 2013

  32. NIDF study of different carbon materials • highly oriented pyrolitic graphite (HOPG) F”(E,θ) 30% H F”(E,θ) 20% H 32 3rd FUSENET PhD Event in York:26thof June 2013

  33. NIDF study of different carbon materials • highly oriented pyrolitic graphite (HOPG) F”(E,θ) 30% H H coverage on HOPGdecreaseswith temperature F”(E,θ) 20% H 33 3rd FUSENET PhD Event in York:26thof June 2013

  34. NIDF study of different carbon materials • yield comparison 34 3rd FUSENET PhD Event in York:26thof June 2013

  35. NIDF study of different carbon materials • yield comparison 35 3rd FUSENET PhD Event in York:26thof June 2013

  36. NIDF study of different carbon materials • yield comparison % H 36 3rd FUSENET PhD Event in York:26thof June 2013

  37. NIDF study of different carbon materials • yield comparison Boron-dopeddiamond: BDD % H % H % H 37 3rd FUSENET PhD Event in York:26thof June 2013

  38. NIDF study of different carbon materials • yield comparison % H % H % H Intrinsicdiamond: ID biasing problems below 400°C % H 38 3rd FUSENET PhD Event in York:26thof June 2013

  39. NIDF study of different carbon materials • yield comparison % H % H Raman spectroscopy: sp3/sp2 BDD sp3/sp2 HOPG % H % H biasing problems below 400°C 39 3rd FUSENET PhD Event in York:26thof June 2013

  40. NIDF study of different carbon materials • sp3/sp2 phase ratio Raman spectroscopy: sp3/sp2 BDD sp3/sp2 HOPG J. Robertson, Materials Science and Engineering, R37 (2002) 40 3rd FUSENET PhD Event in York:26thof June 2013

  41. Conclusions • HOPGgives the highest i-yieldatTroom • IDgives the highest i-yieldatelevatedT: 500°C 41 3rd FUSENET PhD Event in York:26thof June 2013

  42. Conclusions • HOPGgives the highest i-yieldatTroom • IDgives the highest i-yieldatelevatedT: 500°C • properuse of MS diagnostic and modeling allows to determineH coverage on the samplesurface 42 3rd FUSENET PhD Event in York:26thof June 2013

  43. Conclusions • HOPGgives the highest i-yieldatTroom • IDgives the highest i-yieldatelevatedT: 500°C • properuse of MS diagnostic and modeling allows to determineH coverage on the samplesurface • MS combinedwith Raman spectroscopyshows: • the phase ratio sp3/sp2 changes whenincreasingT whichalters the H surface coverageand the i-yield 43 3rd FUSENET PhD Event in York:26thof June 2013

  44. Conclusions • HOPGgives the highest i-yieldatTroom • IDgives the highest i-yieldatelevatedT: 500°C • properuse of MS diagnostic and modeling allows to determineH coverage on the samplesurface • MS combinedwith Raman spectroscopyshows: • the phase ratio sp3/sp2 changes whenincreasingT whichalters the H surface coverageand the i-yield • New materialswith the optimal sp3/sp2 state have to beprobeddeeperunderstandingiscrucial 44 3rd FUSENET PhD Event in York:26thof June 2013

  45. Perspectives • Next steps • prove experimentally the H surface coveragechange with T: • InfraredSpectroscopy • TemperatureProgrammedDesorptionSpectroscopy 45 3rd FUSENET PhD Event in York:26thof June 2013

  46. Perspectives • Next steps • prove experimentally the H surface coveragechange with T: • InfraredSpectroscopy • TemperatureProgrammedDesorptionSpectroscopy • try out new materials: • low work-function materials (Gd, Ba, ...) • large band-gap insulators (Si, GaAs,…) 46 3rd FUSENET PhD Event in York:26thof June 2013

  47. Perspectives • Next steps • prove experimentally the H surface coveragechange with T: • InfraredSpectroscopy • TemperatureProgrammedDesorptionSpectroscopy • try out new materials: • low work-function materials (Gd, Ba, ...) • large band-gap insulators (Si, GaAs,…) • Final steps • Test the chosen material in a real negative ion source (Cybele) equipped with an extraction device and a particle accelerator (MANTIS) in CEA-Cadarache 47 3rd FUSENET PhD Event in York:26thof June 2013

  48. The End Thank you for your attention and time! 3rd FUSENET PhD Event in York:26thof June 2013

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