Characterization of aluminum x-pinch plasmas driven by the 0.5 TW Lion accelerator

Abstract

The x-pinch, obtained by crossing two fine wires at one or more points as the load for the 0.5-TW Lion accelerator, has been used as a bright X-ray source. High-density and high-temperature hot spots are observed at the crossing point(s). From these hot spots, an intense, spatially confined burst of X-rays is emitted which can served as a pump for resonant photopumping lasers. Experimental results concerning the radiation emission using Al x-pinches are reported. The optimum mass loading for different ionization stages of Al ions and the total X-ray energy yields have been examined. The density and temperature of the plasma and the size of the hot spots have been measured. Diagnostics used for these include pinhole photography, streak and framing photography, filtered XRDs, pin diodes, and XUV and soft X-ray spectroscopy. The size of the hot spots is determined from pinhole photographs. No strong Al line radiation for photon energy is found in the range from 300 to 1500 eV. When the He-like or H-like ionization stage is reached, radiation is dominated by resonant K-shell line radiation approximately 1.6 keV in energy. Thus, at the higher hot-spot temperatures, XRDs with filters suitable for the soft X-ray region are used to estimated the Al plasma temperature and to measure the soft X-ray radiation energy yield. The total K-shell line radiation of Al ions is monitored by a pin diode. >