Developing a High Energy Density Platform to Extend Measurement Windows of Hydrodynamic Instability Growth at the National Ignition Facility*

We are developing a high energy density (HED) platform at the National Ignition Facility (NIF) to validate computational models of hydrodynamic instabilities in non-linear and turbulent regimes. The baseline platform resembles (Nagel et. al., POP, 29(3), 2022):  a pair of laser-driven halfraums, with a target composed of two high-density plastic ablators surrounding a low-density carbon foam with a machined initial condition at their interface.  The halfraums launch blast waves into the target, turning the solid interface into an HED plasma interface, that grows by the Richtmyer-Meshkov and Rayleigh-Taylor instabilities.  Starting from this baseline, our approach involves improving spatial resolution by a multiple of ten (25 um to 3um), delaying unwanted late-time shocks for longer undisturbed perturbation growth (15ns to greater than 30ns) and designing perturbations optimized for the improved diagnostics. This will allow us to probe finer details of perturbation growth than previous experiments, which were limited by spatial resolution and complicated by late-time shock interactions (Wang et. al.,  J. Fluids Eng., 140(4), 2018).  We will present the target design and the status of experimental efforts to qualify the platform, including the use of rarefaction-enhanced imaging to detect the unwanted late-time shocks.