Results from X-ray Opacity Experiments on the National Ignition Facility (NIF)

Since 2015 experiments on the NIF have been investigating the x-ray opacities that are used in the radiation-hydrodynamic simulations of the sun, stars, and other high-energy-density plasma. There is little spectrally resolved, experimental opacity data of plasma at the temperatures and densities involved in these calculations. Recent opacity experiments on the Sandia National Laboratories Z machine have shown up to factors of two discrepancies between theory and experiment. At NIF initial opacity data has been taken on iron and oxygen at temperatures around 150 eV and densities around 10²² electrons/cc. Like the Z opacity experiments, our preliminary data seem to indicate discrepancies between the measured and the theoretical opacities, but additional data analysis is needed to correct for known instrumental effects. This data may have implications for modeling the structure of the sun and for determining the age of white dwarf stars.