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Measurements of electron cyclotron emission from the high field side of the TCV tokamak have been made on plasmas heated by second and third harmonic X-mode Electron Cyclotron Heating (ECH) and Electron Cyclotron Current Drive (ECCD). Suprathermal Electron Cyclotron Emission (ECE), up to a factor of 6 in excess of thermal emission, is detected in the presence of X2 ECCD and of X3 ECH. The ECE increases sharply with the local toroidal incidence angle of the X2 EC beams, with a maximum observed at +/- 25°. The measured ECE spectra are modelled using a bi-Maxwellian describing the bulk and the suprathermal electron populations. Suprathermal temperatures between 10-50keV and densities in the range 1E17 - 6 E18 m{-3} are obtained. Good agreement between ECE Suprathermal temperatures and energetic photon temperatures, measured by a hard X-ray camera, is found. For optically thin X3 LFS injection, it is shown that reflection of the beam on the inner walls and absorption on the Suprathermal electron population explain partly the discrepancy between global and first pass absorption measurements.

Additional information

Authors: BLANCHARD P ET AL, Centre de Recherches en Physique des Plasmas, Association EURATOM - Confédération Suisse, École Polytechnique Fédérale de Lausanne (CH)
Bibliographic Reference: An article accepted for publication in the journal 'Plasma Physics and Controlled Fusion'
Availability: Available free of charge from: École Polytechnique Fédérale de Lausanne (EPFL), Ecublens, CH-1015 Lausanne Fax +41-21-6934747
Record Number: 200214709 / Last updated on: 2002-05-10
Original language: en
Available languages: en