Inductively Driven Imploding Plasma System for X-ray Generation

Abstract

High speed cylindrical imploding plasmas have been under investigation at the Air Force Weapons Laboratory as sources of X-rays for nuclear simulation. Results to date indicate that the technique is feasible and large X-ray yields, in excellent agreement with computational models, have been achieved. To make a feasible simulator, very large quantities of electrical energy must be delivered to the load on submicrosecond time scales. The AFWL is studying the use of inductive storage systems as attractive alternatives to the more conventional capacitive energy storage systems. First principles indicate that relatively high efficiency (up to 50%) coupling of electrical energy to kinetic energy of implosion is possible because of the large $\dot{L}$ component of the implosion. Imposing more realistic estimates of the parameters required to meet vacuum power flow criteria drop the estimated efficiency to 20–25%. Investigations of more detailed circuit models indicate the performance of imploding loads to be relatively independent of opening switch parameters including resistance, and opening time within a relatively large range of parameters. Experiments conducted using a 200 kJ, 50 kV, 4 µs capacitor bank measuring the performance of metal foil, electrically-exploded conductor opening switches indicate opening times and final resistance well within the parameters found acceptable in the circuit model.