Investigations into compressible turbulent mix in a convergent geometry plasma environment

A suite of experiments to measure the growth of turbulent mix in a compressible, convergent geometry has been performed on the Omega laser facility at LLE, Rochester NY. These employ a radiographically opaque marker layer to set the initial conditions at the unstable interface and to provide a diagnostic of the induced density gradients. The marker is sandwiched between a plastic ablator and a low-density polystyrene foam cylinder. The implosion is driven by uniform irradiation by 50 laser beams in an impulsive acceleration mode. The ablative drive launches a strong shock, causing the marker to become mixed into both the foam and the ablator. Compressible Richtmeyer Meshkov effects, modified by Bell-Plesset instability dominate the instability growth. The dependence on initial surface roughness is studied along with the time history of the evolution.