Stimulated Brillouin scattering (SBS) is an important physics in inertial confinement fusion. In addition to measuring scattered light, SBS can also be studied by diagnosing SBS-driven ion acoustic waves.[1] In an experiment performed on the Shenguang-III prototype laser facility, collective Thomson scattering (TS) is used to study the spatial growth of stimulated Brillouin scattering in a gas-filled Hohlraum by detecting the SBS-driven ion acoustic wave.[2] High-quality time-resolved SBS and TS spectra are obtained simultaneously in the experiment, and these are analyzed by a steady-state code based on the ray-tracing model. The analysis indicates that ion–ion collisions may play an important role in suppressing SBS growth in the Au plasma; as a result, the SBS excited in the filled gas region is dominant. In the early phase of the laser pulse, SBS originates primarily from the high-density plasma at the edges of the interaction beam channel, which is piled up by the heating of the interaction beam. The results of the experiment and analysis presented in this work will help comprehension of the SBS growth in gas-filled Hohlraums, and could be valuable for future ignition target design.
 

Stimulated Brillouin scattering,Optical Thomson scattering