Multi-megavolt switching in water: Considerations for the Z-R machine

Sandia's Z machine used water as both an insulator in power storage components as well as a switching media. The anomalously high energy density, coupled with its high dielectric strength, allow for a significant reduction in size over a gas insulated design. Moreover, the high currents required to produce ICF demand a low inductance design, which is aided by the high electrical breakdown strength of water. The inductance introduced by the spark channel is a significant source of inductance. The new design will also increase the charge voltage on the water switches and introduces serious concerns regarding the physics of electrical breakdown in water in general and the scaling of water switches in particular. A major concern is the losses associated with water switching in the multi-megavolt regime. In such large pulsed power machines, accurate estimations of switch losses are necessary for new high efficiency pulsed power since the switch losses constitute a major portion of the total energy loss. Previous underestimating of energy losses have caused over predicting the accelerator outputs.