Using Wave-Based Cross-Beam Energy Transfer Simulations to Improve the Ray-Based Models Used in Inertial Confinement Fusion Applications

Ray-based models of cross-beam energy transfer (CBET) are used in radiation--hydrodynamics codes to calculate laser-energy deposition for inertial confinement fusion (ICF) experiments. In direct-drive ICF, calculations suggest that CBET is responsible for a 10{\%} to 20{\%} reduction in laser energy absorption.\footnote{I. V. Igumenshchev \textit{et al.}, Phys. Plasmas \textbf{19}, 056314 (2012).} In indirect drive, ray-based calculations predict full pump depletion of the outer cone beams.\footnote{P. Michel \textit{et al.}, Phys. Plasmas \textbf{20}, 056308 (2013).} Ray-based CBET models require artificial limiters to give quantitative agreement with experimental observables. The recent development of a 3-D wave-based solver (\textit{LPSE} CBET) that does not rely on the paraxial or eikonal approximations allows the limitations of ray-based CBET models to be studied at conditions relevant to laser-driven ICF. The accuracy of ray-based CBET models is limited by uncertainties in the approximations used to account for the experimental realities of beam speckle, polarization smoothing, and interactions at caustics. A physics-based technique is proposed for including the effect of beam speckle in existing ray-based models that gives excellent agreement with the wave-based calculations. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.