KULL Simulations of OMEGA Radiation Flow Experiments*

The problem of radiation flow in a right circular cylinder is of interest for the verification and validation of radiation codes since the flow is analytically analogous to diffusive free molecular flow in a similar geometry.\footnote{E. Garelis and T.E. Wainwright. Phys. Fluids. \textbf{16}, 4 (1973)} Experiments were conducted on the OMEGA laser utilizing a low-density heated-cylindrical-wall target. The targets consisted of a 1.6 mm diameter gold hohlraum containing an on-axis 700 $\mu $m diameter SiO$_{2}$ cylinder inside an 80 $\mu$m thick Ta$_{2}$O$_{5}$ aerogel tube. The FY13 targets also feature ``light-pipe'' diagnostics to measure the progression of the radiation front inside the foam. Simulations were run with the KULL multi-physics code, employing a new laser ray-tracing package. Comparisons of synthetic diagnostics derived from code results to x-ray measurements of drive temperature and heat front propagation provide a methodology to constrain simulation models.