Design of halfraums for x-ray flow experiments on the NIF*

We present a computational study to design and characterize halfraums for the XFLOWS x-ray flow experiments on the NIF. The propagation of radiative heat fronts in High Energy Density experiments has long been a challenging topic to study. Experimental efforts in the past three decades have had success creating relevant data in this regime. However, it has been a challenge for multi-physics simulation tools to accurately and unconditionally predict the behavior of these experiments, a task which is essential to furthering our understanding of Inertial Confinement Fusion and astrophysical processes. The COAX campaign introduced a novel spectroscopic diagnostic to study radiation flows on Omega-60 by measuring temperature and charge state across the heat front [1,2,3]. XFLOWS is the successor to COAX, and is fielded at NIF to access higher temperature regimes with stronger shocks and supersonic flows [4]. There is a need to design and characterize the halfraums that are used to drive these radiative heat waves in order to access the desired hydrodynamic and radiative regimes. Only by accurately characterizing the driving radiation field from the halfraum can we make substantive, quantitative predictions of the resulting flow of energy through the foam.

[1] Johns et al., HEDP 39, 100939, (2021)

[2] Fryer et al., HEDP 35, 100738, (2020)

[3] Coffing et al., POP 29, 8, (2022)

[4] Johns et al., RSI 94, 023502, (2023)