Electron energy distribution function in the divertor region of the COMPASS tokamak during neutral beam injection heating

0489804 - ÚFP 2019 RIV GB eng C - Conference Paper (international conference)
Hasan, E. - Dimitrova, Miglena - Havlíček, Josef - Bogár, Klára - Stöckel, Jan - Varju, Jozef - Popov, Tsv.K. - Komm, Michael - Dejarnac, Renaud - Háček, Pavel - Pánek, Radomír
Electron energy distribution function in the divertor region of the COMPASS tokamak during neutral beam injection heating.
Journal of Physics: Conference Series. Vol. 982. Bristol: Institute of Physics Publishing, Ltd., 2018, č. článku 012002. IOP Publishing. ISSN 1742-6596.
[International Workshop and Summer School on Plasma Physics, IWSSPP 2016/7./. Kiten (BG), 26.06.2016-02.07.2016]
R&D Projects: GA MŠMT(CZ) LM2015045; GA MŠMT(CZ) 8D15001
EU Projects: European Commission(XE) 633053 - EUROfusion
Institutional support: RVO:61389021
Keywords : Neutral beam injection heating * electron temperature * bi-Maxwellian EEDF * Divertor Langmuir probes * first-derivative probe technique
OECD category: Fluids and plasma physics (including surface physics)
http://iopscience.iop.org/article/10.1088/1742-6596/982/1/012002

This paper presents the results from swept probe measurements in the divertor region of the COMPASS tokamak in D-shaped, L-mode discharges, with toroidal magnetic field 1.15 T, plasma current 180 kA and line-average electron densities varying from 2 to 8×1019 m-3. Using neutral beam injection heating, the electron energy distribution function is studied before and during the application of the beam.
The current-voltage characteristics data are processed using the first-derivative probe technique. This technique allows one to evaluate the plasma potential and the real electron energy distribution function (EEDF) (respectively, the electron temperatures and densities).
At the low average electron density of 2×1019 m-3, the EEDF is bi-Maxwellian with a low-energy electron population with temperatures 4-6 eV and a high energy electron group 12-25 eV. As the line-average electron density is increased, the electron temperatures decrease. At densities above 7×1019 m-3, the EEDF is found to be Maxwellian with a temperature of 6-8.5 eV.
The effect of the neutral beam injection heating power in the divertor region is also studied.

Permanent Link: http://hdl.handle.net/11104/0284150