The 9th International Conference on Matter and Radiation at Extremes (ICMRE2026) ( ICMRE2026)

In inertial confinement fusion (ICF), backward stimulated Brillouin scattering (BSBS) pose significant challenges to laser energy deposition and implosion symmetry. While forward stimulated Brillouin scattering (FSBS) has been relatively overlooked among laser-plasma instabilities, partly because its forward direction does not cause energy loss or optical damage. We proposes a novel mechanism for exciting FSBS using dual orthogonally polarized laser beams and investigates its potential role in mitigating collective instabilities.
When a shared ion-acoustic wave (IAW) mode is excited by the two beams, the resulting beat waves between the scattered lights and the IAW can seed FSBS. Simulations reveal that the developed FSBS suppresses both BSBS and the shared IAW mode by driving energy transfer between scattered lights and competing for pump energy. As a result, the total backscattered reflectivity in the dual-beam configuration is reduced to a level comparable to that under single-beam incidence.
This work identifies FSBS not merely as an instability, but as a potential mechanism for mitigating collective instabilities. However, its influence on beam propagation and frequency shift may also affect implosion symmetry and energy deposition in ICF configurations, warranting further investigation under integrated fusion conditions.
 

forward stimulated Brillouin scattering; backward stimulated Brillouin scattering; dual-beam; ion-acoustic wave; inertial confinement fusion