Low-pressure gas breakdown in dual-frequency RF electric fields in nitrogen

Abstract

This paper reports the recorded breakdown curves for dual-frequency (27.12MHz/2MHz and 13.56MHz/50Hz) discharges in nitrogen. Applying the LF voltage shifts the RF breakdown curve to the region of higher voltages and gas pressures, which is associated with the increased loss of charged particles due to the drift in the LF field. At higher LF voltage amplitudes the LF field contributes to gas ionization, the breakdown voltage for the RF discharge decreases and approaches zero when a self-sustained discharge in the LF field ignites. Applying the RF voltage leads to the decrease in the breakdown LF voltage, possibly due to the decrease of electron losses because of the oscillations in the RF field.