Diffuse discharges in SF ₆ and mixtures of SF ₆ with H ₂, formed by nanosecond voltage pulses in non-uniform electric field

Abstract

Results of experimental study of nanosecond diffuse discharge in SF ₆ and gas mixtures of SF ₆ with H ₂, D ₂ and C ₂H ₆ are presented. The aim of this work is to study parameters of discharge between two extended electrodes with a small radius of curvature in SF ₆ and SF ₆ with additives. It was shown that diffuse discharge can be formed in SF ₆ at elevated pressure between blade electrodes with length of 30 cm. It was also confirmed that in a sharply non-uniform electric field a beam of runaway electrons is generated and that the gap breakdown occurs due to ionisation waves which begin on electrodes with small radius of curvature. Laser action in the infrared spectral region was obtained in SF ₆–H ₂ (D ₂, C ₂H ₆) mixtures. The laser output up to 110 mJ was easily achieved which corresponds to ultimate intrinsic efficiency (with respect to deposited energy) of 10%.