Triggering breakdown voltage of a high-current, two-electrode graphite gas switch assisted by ultraviolet pre-ionization.

Abstract

A simple ultraviolet pre-ionization device designed to extend the lifetime of a high current, two-electrode graphite gas switch is described in this paper. The effects of UV-illumination on decreasing the triggering breakdown voltage were studied in theory and experiments. The results showed that UV-illumination can provide extra initial electrons on the cathode surface and make more air molecules in the excited state, which resulted in positive effects in reducing the triggering breakdown voltage and jitter. However, the effects became weak as the pressure increased; the reason of this phenomenon was that the ultraviolet absorption rate of the air molecules increased with the rising pressure, leading to a reduction of the ultraviolet intensity on the discharge gap. The largest value of the triggering breakdown voltage decreased was 13.5 kV under 100 kPa, and the reliable operation gap distance can extend another 1.2 mm, which was equivalent to 500 shots in our experiments.