Implementation of the Low-Noise, 3-D Ray-Trace, Inverse-Projection Method in the Radiation–Hydrodynamics Code HYDRA

Hydrodynamic simulations of direct-drive inertial confinement fusion (ICF) targets require low-noise laser-energy deposition to achieve high-fidelity implosions. Directly driven ICF targets are especially susceptible to laser-deposition noise because of the proximity of the coronal absorption profile to the ablation surface as well as the high laser energy coupling efficiency. Using the inverse-projection method, judicious selection of the simulated laser rays’ origination points dramatically reduces the deposition noise in comparison to random spatial distributions coupled with temporal averaging. The significantly lower ray number density required using the inverse-projection method also improves computational efficiency. The inverse-projection method, originally developed as one part of the Mazinisin 3-D laser ray-trace in the 2-D radiation-hydro code DRACO, has been was extended to the 3-D radiation–hydro code HYDRA. The initial results of 3-D polar-direct-drive implosion simulations demonstrating the improved noise characteristics will be shown as part of the introduction of the inverse-projection method into HYDRA.