Low Jitter, High Voltage, Repetitive Laser Triggered Gas Switches

The Electra pulsed power system at the Naval Research Laboratory is capable of supplying 16 kJ to a low impedance load within 140 ns, and it allows continuous operation of up to 5 pulses per second for several hours. Four laser triggered SF6 gas switches transfer the stored pulse forming line energy to the load. Each switch has a hold-off voltage of more than 1 MV and transfers a charge of 10 mC per shot. This paper describes the redesign of the gas switch with hemispherical electrodes to a flat electrode configuration, which led to an improvement in switch reliability. A one sigma switch jitter of +/-1.2 ns has been achieved for tens of thousands of continuous shots, with an electrode erosion rate as low as 1 mg/C. Detailed statistical analyses are provided when the switches are operated at a SF6 pressure of 0.36 - 0.69 MPa, with a laser trigger energy of 1 - 18 mJ at 266 nm, and a switch hold-off voltage ranging from 0.7 - 1.2 MV.