Determination of the plasma potential and the EEDF by Langmuir probes in the divertor region of COMPASS tokamak

0466022 - ÚFP 2017 RIV GB eng C - Conference Paper (international conference)
Ivanova, P. - Dimitrova, Miglena - Vasileva, E. - Popov, Tsv.K. - Dejarnac, Renaud - Stöckel, Jan - Imríšek, Martin - Háček, Pavel - Pánek, Radomír
Determination of the plasma potential and the EEDF by Langmuir probes in the divertor region of COMPASS tokamak.
Journal of Physics: Conference Series. Vol. 768. Bristol: IOP Publishing, Ltd., 2016, č. článku 012003. IOPscience. ISSN 1742-6588. E-ISSN 1742-6596.
[International Workshop & Summer School on Plasma Physics 2014 (IWSSPP’14)/6./. Kiten (BG), 30.06.2014-06.07.2014]
R&D Projects: GA MŠMT(CZ) LM2011021; GA ČR GAP205/11/2341
Institutional support: RVO:61389021
Keywords : Divertor probes * plasma potential * electron energy distribution function * bi-Maxwellian distribution * electron temperatura and density * first-derivative probe technique
OECD category: Fluids and plasma physics (including surface physics)
http://iopscience.iop.org/issue/1742-6596/768/1

This paper reports experimental data obtained on the COMPASS tokamak by Langmuir probes embedded in the divertor tiles. The measured current-voltage (IV) probe characteristics were processed by the recently published first derivative probe technique for precise determination of the plasma potential and the electron energy distribution function (EEDF). Measurements were performed during L-mode hydrogen and deuterium plasmas with toroidal magnetic field BT =1.15 T, plasma current Ip=180 kA and averaged electron density ne = 8*1019 m−3. The spatial profile of the electron temperatures shows that in hydrogen plasmas in the vicinity of the inner and outer strike points the EEDF can be approximated by a bi-Maxwellian distribution, with a dominating low-energy electron population (4 - 7 eV) and a minority of higher energy electrons (12 - 25 eV). In the private flux region between the two strike points the electron energy distribution function is found to be Maxwellian with temperatures in the range of 7 - 10 eV. In the case of deuterium plasmas at similar conditions of the discharge the EEDFs are found to be always bi-Maxwellian.

Permanent Link: http://hdl.handle.net/11104/0264479