Electron cyclotron non thermal spectra during ohmic and RF assisted discharges on TORE SUPRA

Part of the experimental program on Tore Supra is devoted to the study of the thermal and matter equilibria during RF assisted long discharges (> 30 s). A set of 3 Michelson interferometers viewing perpendicularly and 15 deg apart to the toroidal magnetic field (Dopplers views) has been installed in order to investigate the properties of the non thermal electron population produced by the RF power. When the RF plasma current is carried by high energy electrons, the resonance takes place higher than the electron cyclotron 2nd harmonic for the Michelson view named Bs for 'Blue shifted'. Conversely, the resonance frequency is lowered for the Michelson view named Rs for 'Red shifted'. The upshifted radiation is directly coupled to the receiving antenna while the downshifted radiation is partially absorbed by the optically thick thermal 2nd harmonic. It is then expected some anisotropy between the 3 spectral measurements. In the next section, we report measurements obtained during Lower Hybrid Current Drive experiments for which a significant part of the plasma current is carried by non thermal electrons. The last section concerns unexpected observations obtained during the Ohmic phase. A possible explanation of both situations is proposed with the help of a 3D Fokker-Planck code coupled to an ECE calculation code