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T. Ditmire, K. Shigemori, A. MacKinnon, M. J. Edwards, D. Ryutov, J. Zweiback (Lawrence Livermore National Laboratory), A. M. Rubenchik (University of California, Davis), K. A. Keilty, E. P. Liang (Rice University), B. A. Remington (Lawrence Livermore National Laboratory)
Exploiting the large energy absorption efficiency of intense ultrafast laser pulses in gases of atomic clusters we have conducted a series of experiments on high Mach number shocks in low density gas (< 1019 atoms/cm3). We have produced cylindrical blast waves in these clustering gases and have diagnosed their evolution through a variety of optical probing techniques. We find that it is possible to produce conditions in which radiative effects become important including regimes in which a UV precursor is formed ahead of the blast wave front and situations in which the blast wave trajectory deviates significantly from the classical, Taylor-Sedov predictions. Our experiments agree well with radiative hydrodynamics modeling, confirming the importance of radiative as well as electron heat conduction in the blast wave evolution dynamics. We will also consider the growth of Vishniac-type overstabilities in our experiments..