Relaxation oscillations in a capacitive discharge chamber connected to a peripheral grounded chamber

Abstract

We have observed relaxation oscillations in an argon capacitive discharge connected to a peripheral grounded chamber through a slot with dielectric spacers. The oscillations, observed from time-varying optical emission of the main discharge chamber, show, for example, a high frequency (∼40kHz) relaxation oscillation at 100mTorr, with absorbed power near that for peripheral breakdown, and a low frequency (∼3Hz) oscillation, at higher absorbed power. The high frequency oscillation is found to ignite a plasma in the slot, but usually not in the periphery. We interpret the high frequency oscillations using an electromagnetic model of the slot impedance, coupled to a circuit analysis of the system including the matching network. The model results are in general agreement with the experimental observations and indicate a variety of behaviors dependent on the matching conditions.