Evaluation of the scrape-off-layer plasma parameters by a horizontal reciprocating Langmuir probe in the COMPASS tokamak

18th International Summer School on Vacuum, Electron and Ion Technologies

Dimitrova, M.^1,3 ; Popov, Tsv K.^2 ; Ivanova, P.^3 ; Vasileva, E.^3 ; Hasan, E.^2,3 ; Horáek, J.^1 ; Vondráek, P.^1 ; Dejarnac, R.^1 ; Stöckel, J.^1 ; Weinzettl, V.^1 ; Havlicek, J.^1 ; Janky, F.^1 ; Panek, R.^1

Institute of Plasma Physics, Academy of Sciences of the Czech Republic V.v.i., 3 Za Slovankou, 182 00 Prague 8, Czech Republic^1

Faculty of Physics, St. Kl. Ohridski University of Sofia, 5 J. Bourchier Blvd., 1164 Sofia, Bulgaria^2

Acad. E. Djakov Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee, 1784 Sofia, Bulgaria^3

关键词: Confined plasmas;    Electron energy distribution functions;    Electron pressures;    Last closed flux surfaces;    Low energy electrons;    Measured currents;    Scrape-off layer;    Scrape-off layer plasmas;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/514/1/012049/pdf
DOI  :  10.1088/1742-6596/514/1/012049

来源: IOP

【 摘 要 】

The scrape-off-layer (SOL) parameters in the COMPASS tokamak are studied by using a Langmuir probe mounted on a horizontal reciprocating manipulator. The radial profiles of the plasma potential, the electron energy distribution function and the electron densities are derived from the measured current-voltage probe characteristics by applying the firstderivative probe technique (FDPT). It is shown that close to the tokamak wall the electron energy distribution function is Maxwellian, while in the SOL, in the vicinity of the last closed flux surface and inside the confined plasma, the electron energy distribution function is bi-Maxwellian with a low-energy electron fraction dominating over a higher energy one. The radial profiles of the electron pressure and the parallel electron power flux density in COMPASS are also presented.