Capsule backlighter optimization for the OMEGA opacity experiments*

Our study utilizes Kr gas-filled capsules to examine radiation flows in the COAX, Radishock, and XFOL experiments. To determine the spatial temperature profile of the radiation flow, which is induced by a high-energy laser drive through low-density foam, we leverage X-ray absorption spectroscopy with these gas-filled backlighters. This presentation will highlight our simulation results, particularly those centered around the Kr gas-filled capsule used in the XFOL experiments. To carry out these simulations, we utilized xRAGE, a radiation hydrodynamics adaptive mesh refinement code, in conjunction with a multigroup diffusion package. A total of 24 laser beams with a combined power of 10kJ were used to drive the capsule implosion. The opacity tables were generated using the TOPS code, and for the equation of state the SESAME library was utilized. The results were subsequently post-processed with SPECT3D and the OPLIB opacity tables, generating time-resolved spectra and angular flux. These are then compared with experimental results, contributing to our aim of enhancing our understanding and the reliability of such backlighters in terms of the timing jitter and flash intensity.