X pinches in special configurations

Abstract

Summary form only given. X-pinch plasmas are produced by using two or more fine wires that cross and touch in the middle, in the form of an X, as the load in the anode-cathode gap of a pulsed power generator. They have proved to be very useful for studying high energy density plasmas ranging in Z from Mg to W. The z-pinch process that takes place near the cross point of the wires undergoes m=0 (sausage) instabilities that produce a cascade of smaller and smaller necks in the plasma until one or more micropinches form, emit an X-ray burst, and then explosively disassemble. From the X-ray spectra emitted by Mo, Ti and other wire X pinches, together with X-ray backlighting, these micropinches have been determined to be near solid density and in the keV temperature range for times of the order of 10-100 ps. The object of the experiments presented here was to test wireloading configurations that might accomplish three purposes: 1) enable the load to be changed under vacuum after a pulse using a simple plastic holder, 2) Reliably reduce the number of bright emission spots produced by an X pinch to one, and 3) reduce the number of energetic electrons produced shortly after an X-ray burst. The first of these would allow more pulses per day, the second would allow cleaner X-ray spectroscopy data to be collected (both time-integrated and time-dependent), and the third would reduce the X-ray background when soft (2-8 keV) X-rays are used for imaging on film. There is also the possibility that reproducible loading of holders would produce more reproducible timing of X-pinch X-ray bursts to enable the best possible temporal resolution with time-depended X-ray spectra obtained with an X-ray streak camera.