Optical Emission Characteristics of Electric Discharges in Helium, Argon-Nitrogen Mixtures Under High Frequency Unipolar Voltages

Partial discharges and corona are generally considered as unwanted processes in power systems as they are constant source of power loss and electrical noise (EMI). These effects can further develop into a major problem at the component level, causing insulation deterioration and component failure leading to possible electrical breakdown. The availability of switching power supplies operating at higher intermediate frequencies makes it important to consider the effects of higher operating frequencies on corona and gas breakdown in partial vacuum conditions. This work presents the breakdown characteristics of argon and argon-nitrogen / helium-nitrogen mixtures in partial vacuum conditions subject to unipolar electric fields at 20 kHz. Results of breakdown events are discussed and compared with the results of helium breakdown under similar conditions. This work also presents results of various energy transitions in argon, argon-nitrogen, and helium-nitrogen mixtures as observed from the spectra collected during the breakdown events under unipolar pulsed voltages. These studies provide initial findings on the differences in breakdown behavior between atomic and diatomic excitation processes under unipolar-repetitive pulsed fields in kHz range.