Plasma focus generated by radial foils on COBRA

Summary form only given. Radial foil configurations on the COrnell Beam Research Accelerator (COBRA) provide a convenient setup to study plasma foci using a high Z element such as aluminum. JxB forces push the plasma produced by the foil along the central pillar. Upon reaching the top, it collapses due to a magnetic pinch force, producing a plasma focus. The setup consists of a central pillar 6 mm tall and 1.5mm in diameter surrounded by an array of 6 to 8 vertical rods 20 mm in diameter with 8.5 mm spacing. Anode contact is asymmetrical about the edge of the foil, and the cathode consists of a hollow stainless steel pin with diameter 1.5mm located below the central pillar. The focus is observed through XUV pinhole cameras and by laser shadowgraphy. X-ray transmission intensities collected from PCD probes yield X-ray energies above 900 eV at the time of the focus, which implies an aluminum ionization level of 7 - 8. Numerical simulations using the PERSEUS code describe the plasma evolution and provide estimates of density, temperature and velocity for comparison to experimental data.