Plasma heating by Alfvén wave excitation in the Proto-Cleo stellarator

Alfvén wave heating experiments have been done in the Proto-Cleo l=3, seven field period stellarator. The Alfvén waves were excited by a helical wave launcher which surrounds the entire torus. Doubling of both the electron and ion temperatures was observed with electrons and ions heated independently by the wave. The effectiveness of the heating changes, as predicted by theory, when experimental parameters were varied. Evidence of the existence of Alfvén wave resonant surfaces in the plasma were also observed. Some enhanced plasma loss occurred when Alfvén wave heating was applied to the plasma. Several possible mechanisms for this enhanced loss were studied but no clear explanation was found.