Analysis and Enhancing of Self-Breakdown Voltages of a Multistage Gas Switch

A six-stage gas switch developed for linear transformer drivers is presented in this paper. The switch features an easy-handling structure consisting of stackable cylindrical insulators and brimmed toroidal electrodes. Following an electrode conditioning procedure, the switch and one of its gaps undergo self-breakdown tests by which normal distribution parameters of the self-breakdown voltage at each experimental air pressure are determined. Assuming that all gaps are the same, the switch´s voltage with a 50% self-breakdown probability is predicted as the summed voltage of six gaps which individually have a 10.9% self-breakdown probability of voltage being calculated by using the experimentally determined normal function. The calculated result is 7-14 kV higher than the measured voltage because of a nonuniform voltage distribution which is later confirmed by using unequal gaps. For a more uniform voltage distribution, electrodes are revised to suppress corona discharge, and this revision has finally increased the switch hold-off voltage by 4-6 kV, which is the same as a resistive divider.