A 5-Megavolt, 600-Kiloampere Laser-Triggered Gas Switch for use on Z-R: Comparison of Experiments and Simulations

The Z Refurbishment project is designed to increase the peak current to the load on Z to ~26 MA in a 100-ns wide power pulse. This current is achieved by summing the current from 36 independent pulse-power modules. To meet these requirements, we have designed and constructed an SF6-insulated gas switch that can hold off 5.5 MV and conduct a peak current of 600 kA for over a hundred shots. The gas switch is charged by a Marx generator in ~1 microsecond and transfers about 200-kilojoules of energy and 0.25 Coulombs of charge to a pulse-forming line in a ~150-ns-wide power pulse peaking at 2.5 TW. The gas switch consists of a laser-triggered section holding off 15% of the voltage followed by 25 self-breakdown gaps. The self-breaking gaps are designed to provide multiple breakdown arcs in order to lower the overall inductance of the switch. The gas switch is submerged in transformer oil during operation. In this work, we show how simulation and experiment have worked together, first to verify proper operation of the switch, and then to solve problems with the switch design that arose during testing.