UV-Laser Triggering of 2.8-Megavolt Gas Switches

We are investigating the use of a low-divergence (100, ¿rad) KrF laser to trigger 2.8-MV gas switches for lage pulsed-power systems. Using less than 0.1 J of laser energy, we have demonstrated subnanosecond-jitter triggering (1¿) of these switches, which are insulated with pure SF6, at voltages between 75-90 percent of the self-breakdown voltage of the switch. The time delay between the laser pulse and the switch closure is relatively insensitive to variations in voltage, with delay changing by as little as 1.5 ns between 80-90 percent of the self-breakdown voltage. We also present parametric studies of laser triggering using lenses with different focal lengths at various input laser energies.