Pulsed Breakdown Characteristics of Helium in Partial Vacuum in kHz Range

Summary form only given. Discharge and breakdown studies have been conducted on electrical equipment operating in harsh environments for years. Most of the studies conducted and the techniques developed so far are primarily for terrestrial equipment; this cannot be extended to equipment operating at low pressure in sub-atmospheric conditions. This work presents the preliminary studies on breakdown experiments conducted in helium at partial vacuum conditions for point-to-point electrode geometry using pulsed high frequency signals. A high frequency pulsed voltage signal is applied across the electrodes and the voltage, current, and the light emission characteristics are observed. The applied signal consists of a train of square pulses at frequencies of 50 kHz and 150 kHz. The rise and fall times of these signals are in the range of 20- 30 ns and the duty cycles are varied from 10% to 50%. Results of the breakdown events and the effects of the pulse width (duty cycle) and the pulse repetition rate (signal frequency) in breakdown initiation at low pressure conditions of 0.10 to 10.0 Torr (13.33 to 1333.3 Pascal) are discussed. The optical data collected by a PMT (photomultiplier tube) and the video captured by a fast frame camera as a function of time are also presented.