Analysis of Laser-Imprinting Reduction in Spherical-RT Experiments with Si-Doped Plastic Targets

Nonuniformities seeded by both long- and short-wavelength laser perturbations\footnote{ V. N. Goncharov\textit{ et al.}, Phys. Plasmas \textbf{10}, 1906 (2003).} grow during shell implosion as a result of the RT instability, affecting the target performance.\footnote{S. X. Hu\textit{ et al.}, Phys. Plasmas \textbf{17}, 102706 (2010).} To study the effect of high-$Z$ dopants in the ablator material on laser imprint, spherical-RT experiments have been performed at the Omega Laser Facility using Si-doped plastic targets in the cone-in-shell configuration.\footnote{V. A. Smalyuk\textit{ et al.}, Phys. Rev. Lett. \textbf{103}, 105001 (2009).} Compared to the pure plastic target, radiation preheating from the dopant is expected to decrease the mass density at the ablation front and increase the stand-off distance between the ablation front and laser-deposition region, reducing the imprinting efficiency and the RT growth.\footnote{A. N. Mostovych\textit{ et al.}, Phys. Rev. Lett. \textbf{100}, 075002 (2008).} Analyses of experimental data using two-dimensional \textit{DRACO} simulations for cases with and without dopants will be presented. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.