No pictures this time! The abstract is for the International Conference on the Physics of Shocks (ICOPS), in Washington DC, May 2014. Hopefully it’s accepted, and I can present a poster there. By that time, I might even have done some experiments…
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 [1]. 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 Al or W wire arrays. Radiation enters the gas cell through a window situated 10 mm 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.
1. J. E. Bailey, D. Cohen, G. A. Chandler, M. E. Cuneo, and M. E. Foord. “Neon photoionization experiments driven by Z -pinch radiation”. Journal of Quantitative Spectroscopy & Radiative Transfer, vol. 71 pp 157-168, (2001).