Implosion Simulations Of Radiating Z-pinches

Production of x-radiation using gas puffs and/or wire arrays in a fast z-pinch has been achieved in the laboratory for over a decade. A viable predictive capability using simulations and theory based on first principles is an ongoing effort. This report presents the components of a full simulation model, compares typical results with experimental data, and addresses additional physical issues which may improve both the models and the experimental efficiency. Simulation models include the coupling together of an equivalent circuit model for the pulse power generator with the resistive magneto-hydrodynamic fluid equations, the non-LTE excited and ionized populations, and the radiation transport physics. One-dimensional radial simulations and experimental results are compared in detail for Al wire arrays on the DOUBLE-EAGLE generator. Implosion times and total radiative yields are well matched, but one generally finds differences in the predictions for the yields of x-radiation, for the minimum implosion radii, and for the x-radiation pulse widths. Extension of the models to two dimensions brings in additional physics such as self-generated magnetic fields, Hall term transport, axial motions, turbulent diffusion, and radiating hot spots. The effects of these processes during the implosion phase and their potential for creating a rapid thermalization at assembly on axis will be reported on for Al liner implosions. These results will address the degree to which inherent R-Z asymmetries in the experimental configuration lead to disruption of the z-pinch and thereby prevent the desired uniform radiative collapse seen in 1-dimensional radial models.