Development of predictive modelling for ICF plasmas produced by high-velocity projectiles

First Light Fusion is undertaking research into novel approaches to ICF using intense shock waves driven by high-velocity projectile impactors, requiring a multi-physics approach including microphysics and equation of state (EoS) models for our main simulation tool Hytrac.

The detailed processes governing the microscopic evolution of such states, i.e. heating due to conduction, equilibration and radiation, all require the simple models featured in most hydrocodes to be substantially modified. Here, we focus on thermal conductivity and temperature equilibration.

Hytrac uses EoS tables produced by FEOS, a code based on the well-known QEOS approach. We present improvements to FEOS resulting in robust transitions between model components. Ionisation models beyond the Thomas-Fermi model are also investigated, focusing particularly on detailed atomic shell structure.

A broad sensitivity study has been undertaken, informing prioritisation for physics model development. Comparisons between Hytrac and Helios in idealised geometries show that radiation transport is the greatest source of sensitivity, with EoS also being significant. We find that microphysics is generally unimportant for these simulations, even when processes such as conduction are important to the fuel energetics.