A laser-triggered mini-Marx for low-jitter, high-voltage applications

A relatively simple method for generating high-voltage (/spl sim/200 kV) trigger pulses with low jitter (/spl sim/1 ns) has been developed at the Nike KrF Laser Facility. The output pulse (/spl sim/10 mJ) from a frequency-quadruple Nd:YAG laser is focused between the electrodes of a spark gap, which acts as the first-stage switch in a compact, eight-stage Marx generator. The spark gap is pressurized with a mixture of sulfur hexafluoride and air. The UV (266 nm) laser energy ionizes the SF/sub 6/, creating a spark which triggers the switch. A 20-cm focal length lens is used. The defocusing laser light then illuminates the remaining, self-breaking spark-gap switches in the Marx, pre-ionizing them. The Marx output is approximately 200 kV into 50 ohms, with a risetime of 2 ns. A single Marx is capable of triggering six 100-kV spark gaps via six 65-ohm cables in parallel, with an overall jitter of /spl plusmn/1 ns. A single laser triggers three Marxes; the trigger timing of each can be adjusted independently by changing the laser path lengths. The system uses off-the-shelf components throughout.