Visualizing magnetically driven converging radiative shock generated in Z-pinch foil liner implosion

Abstract

A study of the evolution and structure of magnetically driven converging radiative shock waves generated in Z-pinch foil liner implosion at an 8-MA pulsed-power facility is presented. End-on extreme ultraviolet images show an inward propagating shock that is circular to <±5% as a function of azimuthal angle, with a standard deviation in the emission intensity of <±30%, implying good cylindrical symmetry. The launch time and shock trajectory are determined by linear fitting of the measured data, giving a shock speed of Mach 6. One-dimensional radiation hydrodynamics MULTI-IFE-Z simulations agree with the experimental observations qualitatively and confirm the existence of a radiative precursor. It is demonstrated with experiment and simulation that the radiative shock wave is generated by magnetic piston compression of dense plasma shell. Analytic estimates of the post-shock plasma conditions suggest that these Z-pinch magnetically-driven high-Mach shocks are strongly radiatively cooled. It is applicable to the optically thick downstream, optically thin upstream radiative shock regime; thus, it can be described by three-layer model, which potentially could be applied to scale studies of astrophysical shocks in the laboratory.