Rayleigh–Taylor instabilities in high-energy density settings on the National Ignition Facility

Significance

We present research results on the Rayleigh–Taylor (RT) instability at an unstable interface under high-energy density conditions using the National Ignition Facility at Lawrence Livermore National Laboratory. We can reach pressures in the 100-TPa regime on the Hugoniot, or $\sim$ 500-GPa regime along a quasi-isentrope, allowing the sample under study to remain solid, at planetary interior pressures. We observe RT stabilization ( i) at an ablation front; ( ii) in the presence of a strongly radiative shock; and ( iii) in a unique regime of quasi-isentropic, high pressure, solid-state material flow, where the material strength significantly affects the evolution of a hydrodynamically unstable interface.

Abstract

The Rayleigh–Taylor (RT) instability occurs at an interface between two fluids of differing density during an acceleration. These instabilities can occur in very diverse settings, from inertial confinement fusion (ICF) implosions over spatial scales of $\sim 10^{-3}-10^{-1}$ cm (10–1,000 μm) to supernova explosions at spatial scales of $\sim 10^{12}$ cm and larger. We describe experiments and techniques for reducing (“stabilizing”) RT growth in high-energy density (HED) settings on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. Three unique regimes of stabilization are described: ( i) at an ablation front, ( ii) behind a radiative shock, and ( iii) due to material strength. For comparison, we also show results from nonstabilized “classical” RT instability evolution in HED regimes on the NIF. Examples from experiments on the NIF in each regime are given. These phenomena also occur in several astrophysical scenarios and planetary science [Drake R (2005) Plasma Phys Controlled Fusion 47:B419–B440; Dahl TW, Stevenson DJ (2010) Earth Planet Sci Lett 295:177–186].