Resonant ion heating in a helicon plasma

A resonant ion heating system has been developed for heating ions and controlling the ion temperature anisotropy in a helicon plasma source. The system uses two rectangular coils placed on either side of the cylindrical pyrex vacuum chamber to create a time dependent magnetic field transverse to the steady state axial field. A 1 kW, 25--125 kHz RF generator powers the coils. The parallel and perpendicular ion temperatures in argon plasmas are measured with a laser induced fluorescence diagnostic tuned to a metastable argon ion transition. Ion heating of over 800% has been measured for the perpendicular ion temperatures with an increase of 70% in the parallel direction. This temperature increase occurs for a specific ratio of heating frequency to ion cyclotron frequency. Evidence suggesting that ion Bernstein waves are responsible for the ion heating is presented.