Effect of electron-ion collision on stimulated Raman backward scattering （SRBS） spectrum are investigated by numerical simulations. In the given parameters and plasma condition, the growth rates of SRBS are found to strongly depend on the electron density, and the gap in the SRBS spectrum corresponding to the high electron density could be explained by the collisional damping. In the low density region, a much higher Landau damping estimated by the linear theory makes the collisional damping negligible. However, the present results show that, collisions play a even more important role than known in the linear theory.
Stimulated Brillouin scattering is studied by numerically solving the Vlasov Maxwell system. A cascade of stim- ulated Brillouin scattering can occur when a linearly polarized laser pulse propagates in a plasma. It is found that a stimulated Brillouin scattering cascade can reduce the scattering and increase the transmission of light, as well as intro- duce a bursting behaviour in the evolution of the laser-plasma interaction. The bursting time in the reflectivity is found to be less than half the ion acoustic period. The ion temperature can affect the stimulated Brillouin scattering cascade, which can repeat several times at low ion temperatures and can be completely eliminated at high ion temperatures. For stimulated Brillouin scattering saturation, higher-harmonic generation and wave wave interaction of the excited ion acoustic waves can restrict the amplitude of the latter. In addition, stimulated Brillouin scattering cascade can restrict. the amplitude of the scattered light.
