Improvements in non-LTE atomic kinetics modeling for ICF hohlraums

Predicting the X-ray drive in hohlraums at the National Ignition Facility (NIF) is challenging for radiation-hydrodynamics simulations because of the complex interplay between a myriad of physical processes. Uncertainties in modeling the non-local thermodynamic equilibrium (non-LTE) state of the high-Z wall plasma can explain a significant fraction of the modeled drive discrepancy. We review how improved hohlraum energetics predictions have been achieved by successive improvements to the non-LTE atomic models including employing more complete models for the underlying atomic structure and transitions. Because of their computational expense (both in operations and memory), using our most complete atomic models for inline radiation hydrodynamics calculations has required using GPUs and the latest generation of supercomputers (Sierra at LLNL). We will demonstrate how these simulations can provide valuable benchmark data for complementary off-line approaches (e.g., steady-state non-LTE tables [1]) as well as estimate constraints on the impact of further improvements in non-LTE models.



Prepared by LLNL under Contract DE-AC52-07NA27344.

References

[1] H. A. Scott, J. A. Harte, M. E. Foord and D. T. Woods, Physics of Plasmas 29 (8) (2022)