X pinches in frames under different conditions

Abstract

The experiments reported here were designed to test X-pinch wire-loading configurations using a simple plastic frame that might enable the X-pinch wires to be mounted in the right position under vacuum after a pulse. The first experiments with X-pinches in plastic frames were carried out on the XP generator [1]. In these experiments several frame configurations and materials were tested, and it was found that fiberglass frames were successful in minimizing the current shunting by the frame up to the time of the X-pinch x-ray burst. The XP generator has ∼500 kA load current and a very short ∼ 45 ns rise time, which helps achieve a hot spot before the dielectric frame flashover. The experiments reported here were started on two different generators with different output parameters to determine if it is possible to use the X-pinches in frames on generators with different current pulse parameters. The experiments were carried out on the BIN generator (270 kA, ∼100 ns rise time) at the P. N. Lebedev institute and COBRA (1 MA, ∼100 ns rise time) at Cornell University. Experiments show that to prevent frame flashover and current shunting before the x-ray burst with longer current pulses, it is necessary to reduce the UV radiation from the exploding X pinch wires that reaches the frame early in the pulse. The experiments also show substantially reduced X-ray emission from energetic electrons and secondary soft X-ray bursts following the first X-ray burst. Both of these features are beneficial for using X-pinches for point projection radiography. When flashover of the frames occurs before the moment of hot spot formation, an X pinch produces an intense burst of XUV and x-ray radiation with E≪1 keV, pulse duration ≪10 ns and source size ∼ 1 mm.