A wave-based model for cross-beam energy transfer in direct-drive inertial confinement fusion

Cross-beam energy transfer (CBET) is thought to be responsible for a 30% reduction in hydrodynamic coupling efficiency on OMEGA and up to 50% at the ignition scale for direct-drive (DD) implosions. These numbers are determined by ray-based models that have been developed and integrated within the radiation–hydrodynamics codes LILAC (1-D) and DRACO (2-D). However, ray-based modeling of CBET in an inhomogeneous plasma assumes a steady-state plasma response, does not include the effects of beam speckle, and treats ray caustics in an ad hoc manner. The validity of the modeling for ignition-scale implosions has not yet been determined. To address the physics shortcomings, which have important implications for DD inertial confinement fusion, a new wave-based model has been developed. It solves the time-enveloped Maxwell equations in three dimensions, including polarization effects, plasma inhomogeneity, and open-boundary conditions with the ability to prescribe beams incident at arbitrary angles. Beams can be m...