Design and Characteristics of a High Current Two-Electrode Graphite Gas Switch for the ICF Power System

Abstract

In this paper, a two-electrode graphite gas switch was developed as the main discharge switch for the high-power laser system. A compact Marx generator designed to generate a 20 ns rise-time and −80 kV peak voltage to trigger the main discharge switch. A magnetic switch was designed to block the triggering pulse from the flashlamp load and permit the main discharge current to flow from the capacitor bank to the flashlamp load. The characteristics of the gas switch were measured under a 1.0-MJ capacitive pulsed power module for over 3300 discharge experiments with a total charge transfer 230 kC. The self-breakdown voltage and the surface characteristics of the electrodes indicated that the erosion of the gas switch was uniform. The lifetime was directly dependent on the electrode erosion rate. The gas switch can go on acting at a full current after the graphite electrodes were replaced.