First results from EBW emission diagnostics on COMPASS

0381973 - ÚFP 2013 RIV US eng J - Journal Article
Zajac, Jaromír - Preinhaelter, Josef - Urban, Jakub - Aftanas, Milan - Bílková, Petra - Böhm, Petr - Fuchs, Vladimír - Nanobashvili, S. - Weinzettl, Vladimír - Žáček, František
First results from EBW emission diagnostics on COMPASS.
Review of Scientific Instruments. Roč. 83, č. 10 (2012), 10E327-10E327. ISSN 0034-6748. E-ISSN 1089-7623.
[Topical Conference on High-Temperature Plasma Diagnostics/19./. Monterey, 06.05.2012-10.05.2012]
R&D Projects: GA ČR GA202/08/0419; GA MŠMT 7G10072
Institutional research plan: CEZ:AV0Z20430508
Keywords : Overdense plasma * Conversion * Emission * Tokamaks * Elektron Bernstein waves
Subject RIV: BL - Plasma and Gas Discharge Physics
Impact factor: 1.602, year: 2012
http://dx.doi.org/10.1063/1.4733530

COMPASS tokamak shots at low magnetic field feature overdense plasmas during the extended current flat-top phase. The first harmonic of the electron cyclotron emission is completely cutoff for O and X modes and so the emission caused by electron Bernstein waves (EBWs) propagating obliquely with respect to the magnetic field and undergoing so called EBW-X-O conversion process can be observed. We perform an angular scan of the EBW emission during a set of comparable shots in order to determine the optimum antenna direction. A weak dependence of the radiative temperature on the antenna angles indicates an influence of multiple reflections from the vessel wall. The low temperature at the mode conversion region is responsible for the collisional damping of EBW, which can explain several times lower measured radiative temperature than the electron temperature measured by the Thomson scattering system.
Permanent Link: http://hdl.handle.net/11104/0212326