Large-spatial-scale convective stimulated Raman side scattering under indirect drive conditions

Abstract

The large-spatial-scale stimulated Raman scattering relevant to the SG-III prototype indirect drive parameters is investigated by using the code PHANTAM, which is based on ray tracing and convective amplification. The simulations show that strong stimulated Raman side scattering processes occur in both empty hohlraum and gasfilled hohlraum. The incident laser spot size is found to be the critical factor affecting stimulated Raman side scattering: under the constant laser intensity conditions, the convective gain of stimulated Raman side scattering increases with the laser spot size increasing in both types of hohlraums. In our simulations, the wavenumber mismatch leads to a saturation of the convection gain of the stimulated Raman side scattering in empty hohlraum, while in gas-filled hohlraum the convection gain of the stimulated Raman side scattering keeps increasing as the spot size increases. Under constant laser power conditions, the convective gain of stimulated Raman side scattering decreases while laser spot size increases, and the convective gain of stimulated Raman side scattering decreases faster in empty hohlraum in our simulations. The convective gain of Raman side scattering can be adjusted by laser spot size.