Initial stages of subnanosecond electric pulse breakdown in high-pressure gas discharge gaps

Abstract

The prebreakdown and initial stages of discharge in high-pressure gas filled gaps under the action of subnanosecond high-voltage pulses have been experimentally and theoretically studied. The breakdown appears as a bright flash almost homogeneously filling the interelectrode gap within a period of time on the order of 100 ps. The observed phenomena are theoretically interpreted using a model that takes into account the heating of electrons due to collisions with gas molecules and the electron-impact ionization of these molecules. Calculations show that gas ionization is performed by “hot” electrons and has either a step-or flashlike character, in agreement with experimental observations. The characteristic time of ionization is 10–20 ps. The results lead to the conclusion that, using high-pressure gas discharge switches, it is possible to obtain voltage pulses with front widths on the order of several dozen picoseconds.