Increase in Rosseland mean opacity for inertial fusion hohlraum walls

The Rosseland mean opacity of hohlraum gold walls can be increased by filling in the low absorption gaps in the gold spectrum with one or more additional elements. Using our opacity code STA, we investigated various mixtures. A combination of gold and copper, or nickel, is equivalent or better than the previously proposed gold and gadolinium mixture, and is much easier to fabricate. Other more elaborate mixtures yield even higher opacities. Our simulations are in good agreement with experiment. At the temperatures and densities of interest, non-local-thermodynamic-equilibrium corrections are minor, of order 10%, and not significant in view of the experimental accuracy.