Stimulated Brillouin scattering enhanced by stimulated Raman process near the quarter-critical density

Stimulated Raman scattering can occur near the quarter critical density in direct-drive fusions, and the frequency of Raman scattered light is about half of the incident light frequency. The second harmonic of the Raman scattered light can be produced due to the inhomogeneity density profile. It can serve as the seed of stimulated Brillouin scattering (SBS). When the second harmonic of stimulated Raman scattering light propagates against the incident light, some components will match to the frequency of backward SBS and SBS is induced. Thus SBS could be enhanced greatly.