Collisional magnetic pumping as an efficient way to heat a plasma

This paper describes the application of collisional magnetic pumping to plasma heating. Theoretical solutions giving the heating rate for different magnetic field waveforms of the RF perturbing wave are presented. Numerical solutions to the energy transfer problem reveal a plasma parameter regime in which collisional magnetic pumping is most effective and provide insight into the energy transfer mechanism. It is shown that when the magnetic field waveform is a sawtooth function, the heating rate is proportional to the first power of the field modulation. This is an improvement over the case when a sinusoidal waveform is used, which results in second order heating. To implement experimentally the sawtooth waveform, a switching circuit using solid state power metal-oxide-semiconductor (TMOS) transistors was designed. The circuit is capable of driving a sawtooth shaped unidirectional current in the coil used to generate the RF magnetic field