Photo-ionisation of gas by x-rays from a wire array z-pinch

Summary form only given. An experiment is presented in which the x-ray emission from a stagnated wire array z-pinch is used to photo-ionise gas inside a gas cell. Photo-ionisation studies with x-rays from wire array implosions on the Z facility at Sandia National Labs used a gas cell positioned side-on and at large distances from the pinch
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. Due to the much smaller radiation power from a 1 MA z-pinch, in our experiments the gas cell is mounted in an end-on position, close to the pinch.The experiment is conducted on MAGPIE (1.4 MA, 250 ns current pulse) imploding AI or W wire arrays. Radiation enters the gas cell through a window situated lO rum above the top of the pinch. The window is transparent to photons above 300 eV. Gas composition and pressure are varied to observe different photo-ionisation regimes, in which the mean free path is on the order of, or larger than, the size of the system. We study the dynamics of the photo-ionisation process in gas, and the dynamics of the plasma which is formed. Two-colour multi-time laser-interferometry, Schlieren imaging and optical spectroscopy will diagnose the plasma density and temperature. We present the results of preliminary experiments with this system.