An experimental and numerical study: to investigate the switching characteristics of a field-distortion sparkgap switch in various SF6 admixtures

Abstract

Abstract Pressurized sparkgap switch is one of the major components that is most commonly used in various pulsed-power systems and the stochastic closure time delay (t d ) and jitter (σ d ) in this gas discharge switch has substantial effect on the temporal characteristics of output pulse. Experimental investigations performed with various volumetric concentrations of SF6 in SF6-N2, SF6-dry air and SF6-Ar admixtures evidenced that the intrinsic parameters of the switch such as time delay and jitter were found to be strongly dependent on the nature of gas, volumetric concentration of SF6 in admixture and rate of rise of voltage (dV/dT) of applied trigger pulse for e.g. in SF6/N2 admixture experiments as the concentration of SF6 was increased from 5% to 50% the average time delay and jitter was consequently increased from 278 ns to 413 ns and 17 ns to 56 ns, respectively. The similar increasing trend was observed even in SF6/dry air and SF6/Ar admixture experiments. It was also observed in the investigation that the variation in time delay and jitter is relatively much lesser for the condition when fast rising trigger pulse having slew rates ∼500 V ns−1 is applied than that of trigger pulse with lower dV/dT of ∼3 V ns−1. To further corroborate the stochasticity of streamer discharge in experimented SF6 admixtures, numerical studies have also been carried out by using a Particle-In-Cell/Monte Carlo Collision (PIC/MCC) model. Our experimental and simulation results infer that SF6/Ar admixture with low SF6 concentration is a superior alternative than pure SF6 for pulsed power switching applications.