Rayleigh--Taylor Growth and Spherical Compression Measurements of Silicon-Doped Ablators

X-ray emission from coronal photons emitted by high-atomic-number ($Z)$ layers has been proposed to shape the adiabat in the shell and reduce ablative Rayleigh--Taylor (RT) growth rates during shell acceleration.\footnote{ S. E. Bodner \textit{et al}., Phys. Plasmas \textbf{5}, 1901 (1998).} This effect has been studied with planar-foil experiments to measure the RT growth and low-adiabat spherical implosions to measure the total areal density for a mid-$Z$, silicon (Si), dopant using the OMEGA laser. Growth of perturbations at the ablation interface due to the RT instability is sensitive to the outer-shell adiabat. An implosion target's areal density is sensitive to the inner-shell adiabat and is a sensitive measure of preheat of the inner fuel. Plastic (CH) shells and planar foils are doped with Si with an atomic concentration of 4{\%} to 6{\%}. Experimental data are compared with the hydrodynamic modeling of both the ablation-interface RT growth and the spherical implosion total areal density. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement DE-FC52-92SF19460.