Effect of the launched LH spectrum on the fast electron dynamics in the plasma core and edge

The lower hybrid current drive efficiency in the Tore Supra tokamak was investigated in various cases of launched N/ spectra. By varying the number of energized waveguides, the broadening of the N/ spectrum is varied by a factor 3.5. Weak effect of this broadening is found. The effect of the central value N/0 and the MHD activity is also documented. The parasitic losses of fast electrons in the scrape-off layer are analyzed from infra-red images of the antenna protection limiter. For these experiments performed at constant LH power, the heat flux scales mainly with the RF electric field. The effect of the number of powered waveguides is discussed. (authors)