Effect of electrode surface conditions on the self-breakdown strength and jitter of a high-pressure pulsed gas switch

Measurements were made of the impulse breakdown strength versus pressure for a self-breaking near-uniform-field gas switch. Both roughened and polished electrodes were tested. The breakdown strength was found to be proportional to the pressure for the roughened electrodes; however, the polished electrodes displayed anomalously high but erratic voltage breakdown characteristics at pressures below 5.6 atm. This anomalous behavior was found to be independent of both the electrode material and insulating gas. Electrode roughness or damage appears to play an important role in this process. This damage was significantly reduced by removal of all absorbed machining oils. All efforts to reduce the voltage breakdown jitter, while maintaining the high breakdown strengths, failed. Open shutter photographs of the switch with polished electrodes showed multichannel switch operation which was not expected to occur. Multiple channeling was not observed with the roughened electrodes.