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The Dynamic Hohlraum (DH) radiation on the Z facility at Sandia National Laboratories [R. B. Spielman, W. A. Stygar, J. F. Seamen et al., Proceeding of the 11th International Pulsed Power Conference, Baltimore, 1997, edited by G. Cooperstein and I. Vitkovitsky (IEEE, Piscataway, NJ, 1997), Vol. 1, p. 709] is a bright source of radiant energy that has proven useful for high energy density physics experiments. But the radiation output from a DH on Z needs to be well known. In this paper, a new method is presented for measuring the radiation fluence deposited in an experiment, specifically, an experiment driven by a Z DH. This technique uses a blast wave produced in a SiO2 foam, which starts as supersonic but transitions to subsonic, producing a shock at the transition point that is observable via radiography. The position of this shock is a sensitive measure of the radiation drive energy from the Z DH. Computer simulations have been used to design and analyze a Z foam blast wave experiment. [ABSTRACT FROM AUTHOR]

An analysis of x-ray data from two series of Z-pinch shots taken on the short current-risetime Saturn accelerator at Sandia National Laboratories [Proceedings of 6th International IEEE Pulsed Power Conference, Arlington, VA, edited by P. J. Turchi and B. H. Bernstein (IEEE, New York, 1987), p. 310] is presented. In one series, the array radius was held constant and the array mass was varied; in the other series, the array mass was held constant and its radius varied. In both sets of experiments, large wire-number loads (N>=93) of aluminum were used in contrast to earlier small wire-number aluminum array experiments on Saturn where N≤42. Average electron temperatures and ion densities were inferred from the data. In addition, from the measured size of the emission region of K-shell x rays and from the inferred ion density, a fraction of the total array mass that participated in the K-shell emission was inferred and found to be directly correlated to the K-shell yields that were measured. This paper also demonstrates that the yields varied as a function of array mass and radius in much closer agreement with predictions [J. Appl. Phys. 67, 1725 (1990)] than had been observed in the earlier small wire-number experiments. Thus, a serious misperception that the reason for the early disagreement was in the calculations and not in the experiments is corrected. These predictions were made using one-dimensional (1D) magnetohydrodynamics calculations. The density and temperature trends inferred from the data analysis are well-behaved and consistent with the 1D calculations. This data analysis confirms the importance of achieving uniform plasma initial conditions and implosion symmetry when comparing computer code calculations with experiment. When the wire number of an array load is increased, a more uniform shell of plasma is calculated initially as the wires explode and, as the plasma stagnates on axis, the x-ray powers and yields are found experimentally to appro... [ABSTRACT FROM AUTHOR]