Switch evaluation test system for the National Ignition Facility

Flashlamp pumped lasers use pulsed power switches to commute energy stored in capacitor banks to the flashlamps. To lower the total cost of these switches, Sandia National Laboratories has a research program to evaluate large closing switches. The particular application in which we are interested is the National Ignition Facility (NIF). The target value of the energy switched by a single device is 1.6 MJ, from a 6 mF, 24 kV capacitor bank. The peak current is 500 kA. The lifetime of the NIF facility is 24 thousand shots. There is no switch today proven at these parameters. The goal of the experiments at Sandia is to test switches with the full NIF wave shape, and at the correct voltage. The Sandia facility can provide over 500 kA at 24 kV charge voltage. The facility has 6.4 mF total capacitance, arranged in 25 sub-modules. The modular design makes the facility more flexible (for possible testing at lower current) and safer. For pulse shaping (the NIF wave shape is critically damped) there is an inductor and resistor for each of the 25 modules. Rather than one large inductor and resistor, this lowers the current in the pulse shaping components, and raises their value to those more easily attained with lumped inductors and resistors. We show the design of the facility, and show results from testing conducted thus far. We also show details of the testing plan for high current switches.