Low-Frequency Relaxation Oscillations in Capacitive Discharge Processes

Low-frequency (2.72--3.70Hz) relaxation oscillations at 100mTorr at higher absorbed power were observed from time-varying optical emission of the main discharge chamber and the periphery. We interpret the low frequencyoscillations using an electromagnetic model of the slot impedance with parallel connection variational peripheral capacitance, 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 behaviours dependent on the matching conditions.