Equal-Channel-Angular-Extrusion Be-Cu as a NIF Ablator

Equal channel angular extrusion (ECAE) Be-Cu is an alloy that may be useful as an ignition target ablator at the National Ignition Facility (NIF). Planar samples have been diamond turned to create a 0.25-$\mu $m amplitude sinusoid on one side. These have been mounted in hohlraum targets at the OMEGA laser and driven by a pressure approaching 2 Mbar and a radiation temperature that peaks near 160 eV in $\sim $6 ns. The resulting growth of the Rayleigh-Taylor instability has been examined with x-ray backlighting. With face-on imaging, we see no growth. However, with side-on radiography, parallel the grooves of the sinusoid, the twenty-times-greater \textit{$\rho $r} permits us with a 16-frame gated x-ray imager to see modulation of the Be-Cu foil as it is launched out of the end of the hohlraum. The x-ray transmission is deduced. Hydrodynamic modeling matches the radiation temperature of the hohlraum, and calculations are compared to the velocity of ejection of the sample. A 2D-Rad-Hydro code is used to calculate the sample mean x-ray mass absorption coefficient for the broadband backlighter energy. The time-dependent growth factor of the instability is estimated.