Suppressing thermal energy drift in the LLNL Flash X-Ray accelerator using linear disk resistor stacks

This paper addresses thermal drift in sodium thiosulfate liquid resistors and their replacement with linear disk resistors from HVR Advanced Power Components. Sodium thiosulfate resistors in the FXR induction linear accelerator application have a temperature coefficient of ~1.8%/°C. The FXR Marx banks send an 8kJ pulse through eight 524 cm³liquid resistors at a repetition rate of up to 1 every 45 seconds. Every pulse increases the temperature of the solution by ~0.4°C which produces a 0.7% change in resistance. The typical cooling rate is ~0.4°C per minute which results in ~0.1% energy drop per pulse during continuous pulsed operations.