A laser-triggered spark gap for 750 kV, 20 ns risetime impulse generator

A description is given of a nanosecond-risetime, 750-kV spark gap impulse generator that is triggered by an ultraviolet laser pulse (KrF, λ=249 nm). The SLITS (SF₆ laser-induced triggering system) is an add-on fast switching capability that makes use of the existing equipment (Marx, AC or DC) and can be triggered at voltages as low as 10% of the spontaneous breakdown voltage of the gap. The output voltage can be varied simply by adjusting the internal delay of the laser or the source voltage, eliminating the awkward adjustment of the sphere gaps required in a conventional pulse generator. Jitter is reduced too less than 10 ns at 80% of the spontaneous breakdown voltage, making the output waveform highly reproducible