Numerical Investigation of Radiative Heat Fronts in Optically Thick Materials

When an optically thick body is exposed to an intense radiation field, its temperature equilibrates with the radiation field by the propagation of a nonlinear heat front. This causes the surface of the body to ablate and a shock to pass into the interior. Radiative heat fronts of this type have been created in recent experiments performed on the OMEGA laser system in the context of studying radiation-driven implosion of molecular gas clouds. We provide results of simulations performed with the CRASH radiation hydrodynamics code to be used for the design of future experiments. These simulations incorporate details of the system created in these experiments (spot size, time-dependent drive). We provide details of shock structure and strength from simulations for comparison with experimental radiographs, and we interpret an apparent bow-shock feature observed in radiographs. Furthermore, we evaluate the potential use of self-similar solutions, which may allow estimation of quantities for experimental design without further simulations.