Simulations of the impact of ablator micro-structure on ICF implosions

ICF implosions using high-density carbon (HDC) ablators have achieved better fusion performance than other ablator types, but the final fuel compression is less than needed for robust fusion burn. One hypothesis for reduced compression is that the internal structure of HDC seeds hydrodynamic instabilities. HDC is composed of anisotropic microcrystalline grains with lower density between grains and may have complex dynamics near the melt transition. Measurements using the two-dimensional VISAR diagnostic at the Omega laser facility revealed velocity modulations on the shock wave that are larger with HDC ablators than with CH or Be. This data is used to construct a density modulation that is applied to simulations of ICF implosions. This talk explores the impact of this micro-structure modulation on the compression and instability growth of DT layered implosions on the National Ignition Facility.