Platform-dependent advantages and challenges of laboratory stellar-opacity measurements

The accuracy of iron and oxygen opacity calculations critically affects solar/stellar modeling and numerous high-energy-density (HED) plasma simulations. The absence of benchmark opacity experiments introduces unknown uncertainty into these plasma simulations. The first iron opacity measurement at solar interior temperatures, performed at the Z-machine at Sandia National Laboratories, uncovered a greater-than-expected discrepancy between measured and modeled iron opacities at Te = 170-195 eV, ne = 1e22-4e22 e/cc. This can help resolve discrepancies between solar models and observations, but it also incited controversy within the HED community. An alternative experimental method developed at the National Ignition Facility (NIF) serves to independently examine these findings. The Z-machine employs an area backlight approach, while NIF uses point-projection. These methods offer unique benefits and challenges because of platform specificity. This talk discusses how these approaches complement each other and how this national collaboration will help provide unbiased constraints on the accuracy of iron and oxygen opacity.

Sandia National Laboratories is a multimission laboratory managed and operated by NTESS LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. DOE’s NNSA under contract DE-NA0003525.