Measurement of ablative Richtmyer-Meshkov growth in planar geometry

Summary form only given. Inertial confinement fusion requires the passage of multiple shocks through the plastic ablator of a capsule containing deuterium-tritium (DT) fuel. The shocks cause the capsule to implode with a factor of >;35 compression. The ablation process driving these strong shocks, however, causes any mass perturbations on the outside of the capsule to grow due to the ablative Richtmyer-Meshkov instability whose primary role is to seed later time Rayleigh-Taylor. Unstable growth of these perturbations may lead to jetting and mix of cold ablator material into the DT fuel thus hindering ignition. In order to validate design calculations of this effect, experiments at the Omega laser measured the growth of imposed two-dimensional perturbations (bumps) in a CH planar foil. In these experiments, a half Hohlraum is heated by up to 800 J of laser light, creating a radiation temperature of up to 70 eV. The soft x-ray ablation drives a shock into the CH with a velocity measured to be 11 microns/ns. The resulting time evolution of the areal density perturbation, first growing to ~2× of initial then decreasing as expected from theory, was measured. Simulations of these experiments were found to be in very good agreement with the LEOS 5310 equation of state for CH.