Plasma heating at the fundamental ion cyclotron frequency in the L-2 stellarator

Experiments on ion-cyclotron-resonance heating of a hydrogen plasma in the L-2 stellarator are reported. The results show that the plasma can be heated efficiently at the fundamental ion cyclotron frequency. The ion temperature reaches values --300 eV in the course of the heating; i.e., the ion temperature is increased to a level roughly four times that in the ohmic heat stage. The increase in the plasma density and the influx of impurities when the rf pulse is applied display no resonance behavior or functions of the magnetic field, in contrast with the ion heating.