Relaxation oscillations in a bounded magnetized plasma

Low frequency modulation of the transmitted and reflected microwave power from a thin plasma disc is observed. The plasma is produced by electron cyclotron resonance (ECR) and is sustained in a steady state by absorption at the upper hybrid frequency. Adjustment of the input power and the magnetic field initiates a superimposed oscillating absorption process. The electron density and/or temperature is found to oscillate at the same frequency which is found to fit the simple ion acoustic dispersion relation f=csub(s)/lambda where csub(s)=(kTsub(e)/msub(i))sup(1/2). Since a number of other experiments in entirely different geometry exhibit what appears to be the same phenomena, the occurrence of these relaxation oscillations in microwave plasma interactions would seem to be fairly common. (author)