Shocked Variable-Density Turbulence Studies on the VST

Inertial confinement fusion (ICF) is the process of collapsing millimeter size capsules to generate fusion energy in the compressed fuel. These capsules are comprised of multiple layers of varying densities, and high energy deposited on their outer shells causes the collapse processes. The energy deposition process also creates multiple shocks that traverse these multi-layer capsules, inducing the Richtmyer-Meshkov instability (RMI) as each shock crosses a density boundary. We know from single fluid experiments that multiple shocks of the RMI lead to turbulence, and one can anticipate that shock-turbulence interactions (STI) occur in ICF capsules. STI have been well studied in constant-density fluids, but not in a variable-density setting. The Extreme Fluids team at LANL has developed a series of experiments using the Vertical Shock Tube (VST) to study shock-turbulence interactions. A turbulent layer is setup between air-SF₆ (A ~0.6) and is characterized pre-shock and post-shock. Simultaneous density and velocity measurements are used to look at how the turbulence is affected. By adjusting experimental parameters, we are able to study the effects of STI at different turbulent intensities and Mach numbers. Results from recent experiments will be presented.