Structure in mixed element plasmas on the Z-accelerator at Sandia National Laboratories

Summary form only given. Mixed-element plasmas were generated on the Z-accelerator by imploding nested arrays of aluminum wires and nickel-clad titanium wires. For the experiment examined in this work, the outer array used aluminum wires and the inner array used nickel-clad titanium wires (adding nickel cladding to titanium wires allows the fabrication of smaller diameter titanium wires). The plasmas were created by the discharge of the Z-accelerator, which provided a linearly rising current peaking at 18 MA in 90 ns. The Z-pinch effect heated and compressed the wires, creating helium- and hydrogen-like ions. The resulting plasma emitted characteristic X-rays, recorded on a variety of instruments. We recorded time-resolved spectra from the aluminum plasma in addition to spatially-resolved but time-integrated spectra from the titanium and nickel plasmas. We recorded the output power from the plasmas using photo-conductive diamonds (PCDs) filtered to pass discrete energy-bands. We also recorded time-resolved pinhole camera images of the plasmas along the axis of the plasma. Combining these measurements and performing detailed analysis has provided a comprehensive model of the structure in this radiating plasma. This model indicates a hot core (having an electron temperature of a few keV) of titanium and nickel ions, surrounded by a cooler (electron temperature of approximately 900 eV) blanket of aluminum ions with a smaller fraction of Ti and Ni ions. The surrounding blanket of aluminum only contains 20% of the initial aluminum in the array, suggesting that the remaining 80% is radiating at lower energies and is at a lower temperature.