Plasma diagnostics for x-ray driven foils at Z

We report the development of techniques to diagnose plasmas produced by x-r ay photoionization of thin foils placed near the Z-pinch on the Sandia Z Ma chine. The development of 100+ TW x-ray sources enables access to novel pla sma regimes, such as the photoionization equilibrium. To diagnose these pla smas one must simultaneously characterize both the foil and the driving pin ch. The desired photoionized plasma equilibrium is only reached transiently for a 2-ns window, placing stringent requirements on diagnostic synchroniz ation. We have adapted existing Sandia diagnostics and fielded an additiona l gated three-crystal Johann spectrometer with dual lines of sight to meet these requirements. We present sample data from experiments using 1-cm, 180 -eV tungsten pinches to photoionize foils made of 200 Angstrom Fe and 300 A ngstrom NaF co-mixed and sandwiched between 1000 Angstrom layers of Lexan ( C16H14O3), and discuss the application of this work to benchmarking astroph ysical models. (C) 2001 American Institute of Physics.