The Atlas load protection switch

Atlas is a high-energy pulsed-power facility under development to study materials properties and hydrodynamics experiments under extreme conditions. Atlas will implode heavy liner loads (m/spl sim/45 gm) with a peak current of 27-32 MA delivered in 4 /spl mu/s, and is energized by 96, 240 kV Marx generators storing a total of 23 MJ. A key design requirement for Atlas is obtaining useful data for 95% of all loads installed on the machine. Materials response calculations show current from a prefire can damage the load requiring expensive and time consuming replacement. Therefore, we have incorporated a set of fast-acting mechanical switches in the Atlas design to reduce the probability of a prefire damaging the load. These switches, referred to as the load protection switches, short the load through a very low inductance path during system charge. Once the capacitors have reached full charge, the switches open on a time scale short compared to the bank charge time, allowing current to flow to the load when the trigger pulse is applied. The time window of vulnerability for load damage is thus substantially reduced. The design of the load protection switches and test results are presented.