Comparative analysis of time-resolved and time-integrated x-ray data from long pulse Z-pinch implosions on Saturn

Abstract

Two series of Al:Mg wire array Z-pinch implosions were performed on the Saturn pulsed-power generator [R. B. Spielman et al., in Proceedings of the 2nd International Conference on Dense Z-Pinches, Laguna Beach, CA, 1989, edited by N. R. Pereira, J. Davis, and N. Rostoker (American Institute of Physics, New York, 1989), p. 3]. In one series, the wire number was varied, in the other, the load mass was varied. In all cases an initial array diameter of 40 mm was maintained. Sufficient x-ray data were obtained in these experiments to allow the plasma conditions to be inferred by matching x-ray data to that calculated by a collisional-radiative equilibrium (CRE) model. In fitting the data, the plasma has been assumed to be either uniform [zero dimension (0D)] or to vary one-dimensionally (1D) with radius. On one shot, a comparison of these two methods of data analysis performed with both time-resolved and time-integrated data has been carried out. While the same trends in plasma conditions as a function of load mass and wire number are seen, the uniform plasma assumption yields higher electron temperatures, lower core densities, but higher K-shell radiating mass fractions than those obtained from the 1D assumption. When comparing time-resolved and time-integrated spectroscopic data, a pronounced difference is seen in a density-sensitive line ratio whose time-resolved values corroborate experimental evidence that much of the K-shell radiation is emitted from a high density core plasma of spatial extent less than about 300 μm.