The 8th International Conference on Matter and Radiation at Extremes (ICMRE2025)

26 / 2025-02-27 09:10:07

Simplified Ray-Based Modeling for Self-Cross Beam Energy Transfer (Self-CBET) in Broadband Lasers

cross beam energy transfer,,simplified ray-based simulation,,broadband laser

We investigated the suppression of intra-beam cross-beam energy transfer (self-CBET) in broadband lasers using a simplified ray-tracing model based on classical CBET theory. Building on spectral discretization methods, we decompose a single broadband beam into 20 sub-beams with randomized phases and Gaussian-distributed frequencies (0-5 THz bandwidth), a key departure from prior multi-beam CBET models that neglect spectral broadening. Simulations predict a ~10% reduction in self-CBET-driven energy transfer for broadband configurations compared to narrowband cases, aligning with wave-based ion-acoustic decoherence mechanisms reported. However, the model reveals limited sensitivity of total laser absorption to bandwidth variations, a discrepancy primarily attributed to incomplete spectral decoherence from finite sub-beam discretization. Secondary factors include steady-state plasma approximations (neglecting transient flows) and omitted nonlinear saturation at high intensities. Comparisons with hybrid-kinetic codes (e.g. CBETor) validate computational efficiency but expose unresolved discrepancies in caustic regions where wave effects dominate. These results correlate with OMEGA laser experiments reporting 10-20% CBET-induced absorption losses and highlight challenges in diagnosing broadband-driven improvements due to weak absorption sensitivity. The work underscores the need for dynamic plasma coupling and refined spectral decoherence models to advance inertial confinement fusion laser designs, bridging ray-based and wave-based approaches for robust self-CBET mitigation.