Laser–Plasma Energy Coupling Bookkeeping for Direct-Drive Inertial Confinement Fusion: An End-to-End Ledger from Incident Laser Energy to Implosion Kinetic Energy

An end-to-end energy ledger for direct-drive inertial confinement fusion in which every entry is computed from a stated formula: inverse bremsstrahlung and resonance absorption, a scattered-light loss term, the two-plasmon-decay hot-electron scaling of Hu et al. (2013), the ablation pressure and mass ablation rate scalings of Dahmani (1992), and an ablative rocket model with an enthalpy correction. For an OMEGA-scale case at 351 nm and 2e14 W/cm2 the absorbed fraction is 0.914, hot electrons carry 0.46% of the incident energy, the hydrodynamic efficiency is 0.113, and the end-to-end coupling (shell kinetic energy per incident laser energy) is 0.103 (1.31 kJ from 12.72 kJ). At 1e15 W/cm2 the coupling falls to 0.067 despite higher ablation pressure and kinetic energy, and at 1053 nm it falls to 0.027. A sensitivity analysis ranks each bookkeeping term. All numbers are produced by the deposited script compute.py.