Progress towards validating a high energy density platform to capture the non-linear to turbulent transition of hydrodynamic instability growth at the National Ignition Facility

We present our progress towards developing a high energy density (HED) platform at the National Ignition Facility (NIF) to validate Large Eddy Simulations (LES) in the transition from the non-linear to turbulent regime. Our baseline HED platform design is composed of two laser-driven halfraums and a target composed of two high-density plastic ablators and a low-density carbon foam. Building off of our baseline HED platform design, we have selected an initial perturbation composed of a single-mode sinusoidal perturbation, which is machined at the foam-plastic interface. When the halfraums are driven, shock waves are sent into the target turning our solid interfaces into a HED plasma interface. These plastic-foam interfaces grow by Richtmyer-Meshkov and Rayleigh-Taylor instabilities. Our choice of ablation thicknesses and foam densities delay unwanted late-time shocks for longer, undisturbed perturbation growth in the non-linear regime when compared with the previous “Reshock” campaign. Additionally, our choice of initial perturbation is predicted to transit from the linear to a turbulent state within our experimental window. These improvements to our baseline HED platform design result in a longer measurement time window which, coupled with experimental diagnostics with higher spatial resolution, will allow us to probe the finer details of hydrodynamic instability growth in the HED regime as compared with previous experiments.

Prepared by LLNL under Contract DE-AC52-07NA27344