Plasma heating and sustainment in the ion cyclotron range of frequencies on the stellarator W7-AS

On the stellarator W7-AS resonant and non-resonant ICRF heating scenarios were successful both in increasing the ion and electron temperature of ECRH or NBI target plasmas and in sustaining the plasmas under steady-state conditions. The investigated scenarios were: D(H), 4He(H) minority heating (minority species in brackets), D/H mode conversion heating and second harmonic H heating. In all cases density control was possible and no significant increase in impurities was observed. The heating efficiencies were comparable to tokamaks. (author)