Time Resolved X-ray Plasma Emission in low Current X-Pinches

Summary form only given. Experiments investigating the long time scale X-ray emission from X-pinches have been performed on a compact laboratory-scale pulser. The device has a maximum current of 80 kA with a rise time of ~40 ns, and wire materials including aluminum, nickel, stainless steel, molybdenum and tungsten were studied. Time resolved X-ray signal data have been recorded and analyzed, which included a set of Si diodes filtered using Ross pair filter sets. Simultaneous optical probing techniques (Schlieren and interferometry) were used to correlate X-ray emission with pinching of the plasma and gap formation. A scan of wire number and wire material was carried out whilst maintaining constant mass in the X-pinch. Various features including peak timing, number of peaks, FWHM, rise time, and time varying spectrum are reviewed. Results show that typically low Z metals have single long rise time peaks, while high Z materials have multiple sharp peaks. This analysis shows that the material and configurations play a profound role in the X-ray emission characteristics of the X-pinch. In addition, the variation of emission from bare Mo wires and Mo wires coated with a thin layer (0.04 mum) of gold was investigated. In cases with the gold coating, 3 distinct, well spaced peaks are observed in the X-ray emission, while uncoated wire signals generally comprise one primary and anywhere from 1-3 secondary peaks. Within a single shot, one can observe peaks with different profiles, and bare Mo X-pinches give peaks with rise times from 2-8 ns. This variable emission suggests that X-rays are produced by various mechanisms, which will be presented and discussed.