A Platform for Opacity Experiments on the NIF*

Radiation-hydrodynamic simulations of the sun, stars, and other high-energy-density plasma require knowing the x-ray opacities of the constituent materials. These opacities are generally calculated from theory. There is little spectrally resolved, experimental opacity data of plasma at the temperatures and densities found in the interior of stars. Recent opacity experiments on the Sandia National Laboratories Z machine have shown up to factors of two discrepancies between theory and experiment. To help resolve this discrepancy an experimental platform for doing opacity experiments has been developed on the National Ignition Facility (NIF). The effort has been led by scientists from both Los Alamos and Lawrence Livermore National Laboratories with support from Sandia, the Nevada National Security Site, General Atomics, the Laboratory for Laser Energetics, and the University of Texas at Austin. Initial opacity data has been taken on both iron and oxygen at temperatures around 150 eV and densities around 10²² electrons/cc. This data will be compared with theory and with similar data obtained at the Z facility. This data may have implications for modeling the structure of the sun and the age of white dwarf stars. The current status and future plans for the experiments will be presented.