Evidence of Increased Laser Energy Coupling with Pure Silicon Ablators in Laser Direct-Drive Inertial Confinement Fusion Implosions

Hydrodynamic simulations with high-Z ablators indicate a uniform increase absorption that would lead to higher implosion velocities in laser-direct-drive (LDD) inertial confinement fusion (ICF) experiments. An increase in implosion velocity achieved exclusively by replacing the ablator (without having to intentionally adjust the IFAR or adiabat) could lead to higher primary nuclear yields in cryogenic implosions at the expense of additional radiation preheat by introducing a high-Z material. One candidate that has been studied recently is a pure Silicon 2-μm thick ablator where simulations do exhibit more laser energy absorption without an increase on hot-electron production. Preliminary experimental results will be shown that an increase in laser absorption and decrease in hot-electron production has been observed generating a higher yield-over-clean (YOC) as compared to tradition plastic CH ablators with a small fraction (2% and 6% atomic fraction) of Silicon. Simulations to explore an optimal high-Z dopant with minimal radiation preheat and increased implosion velocity will be presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856.