VARIATIONS IN VACUUM GAP LOCATION IN A MICROSECOND PLASMA OPENING SWITCH

The process of vacuum gap formation in a microsecond plasma opening sw itch has been studied using a He-Ne laser interferometer, Time and spa tially resolved density measurements are performed in the plasma openi ng switch, showing a density decrease during switch opening in almost the whole interelectrode gap. Despite fine triggering accuracy and gen erally good shot-to-shot reproducibility of voltage and current wavefo rms, measurements made with the same laser beam location indicated rem arkable shot-to-shot variation. The unstable formation of the vacuum g ap in the microsecond plasma opening switch may be a major limiting fa ctor for efficient switch operation. (C) 1997 American Institute of Ph ysics.