Alfvén-Wave Heating in the Proto-Cleo Stellarator

Global excitation of Alfvén waves in the Proto-Cleo $l=3\mathrm{}$ stellarator was accomplished by exciting a helical winding corresponding to a $q=3\mathrm{}$ rational surface with a pulsed, high-power rf source. A doubling of both the electron and ion temperatures was observed, and a slight increase in the ratio of the temperatures with and without rf heating occurred at the predicted resonance locations. Enhanced loss also occurred during heating, with 2.5-kHz oscillations observable in a microwave interferometer signal after heating.