PARAMETRIC AMPLIFICATION IN AN rf SUSTAINED PLASMA CAPACITOR

The experimental results of a radiation-induced instability in a completely rf sustained plasma capacitor discharge are discussed. Nonlinear coupling between electron plasma modes and ion-acoustic modes has been observed resulting in a four-frequency parametric interaction. By reducing the microwave pump power below the power threshold required for the instability, the rf pumped plasma capacitor is able to amplify a separately applied cw input signal when this signal is in the vicinity of one of the parametric resonances. Experimental results are presented which show the effect of the capacitor size and input pump power on the parametric interaction.