114 / 2025-03-14 23:51:01

Nonlinear amplification of laser-plasma instabilities and hot electron generation driven by broadband lasers

laser plasma instabilities,broadband laser,hot electron,Stimulated Raman scattering (SRS)

Broadband lasers are widely regarded as promising candidates for suppressing laser-plasma instabilities (LPI), with the potential to significantly enhance ablation pressure and enable high-gain ignition in inertial confinement fusion. Experimental results from Kunwu, the world’s first operational broadband laser facility, confirm that broadband lasers effectively suppress stimulated Brillouin scattering (SBS). However, their impact on stimulated Raman scattering (SRS) and hot-electron generation remains less understood. In this study, we employ statistical optics and numerical simulations to investigate the impact of broadband lasers on LPIs coupled with electron plasma waves. Our analysis reveals that reduced temporal coherence in broadband lasers leads to intensity fluctuations and the formation of high-intensity, long-lifetime local pulses. When these pulses exceed a critical threshold, they enable the nonlinear amplification of scattered light within the pulse, generating more scattered light and hot electrons than predicted by linear theory. These results advance the understanding of broadband laser-driven LPI behavior, provide a candidate explanation for the Kunwu experiments and offer insights into optimizing broadband laser designs for more effective LPI suppression.