Modeling shocks interacting with radiation waves in the Radishock experiment

In the Radishock experiment, a radiation wave is indirectly driven into a low-density foam and interacts with a directly driven, counter-propagating shock. The interacting waves produce a spike in energy density, with a temperature greater than the local temperature of the individual waves. As in the successful predecessor experiment COAX, the primary diagnostic uses absorption spectroscopy at many locations down the cylindrical target, enabling a spatial temperature inference of the radiation wave and its interactions with the shock. Combined with a radiography diagnostic that is capable of imaging the shock and interaction features, we are able to study and inform model predictions of the interaction spike phenomenon. We present a physical description of these wave interactions and early comparisons between radiation-hydrodynamic simulations and the data from our successful experiments.