Controlling stimulated brillouin backscatter with beam smoothing in weakly damped systems.

We derive an analytical estimate of the effect of temporal smoothing of laser beams on stimulated Brillouin scattering (SBS) in a regime relevant to indirect drive ignition. We predict a strong reduction of SBS in the gold plasma expanding from the Hohlraum wall with temporal smoothing. This is a new regime far above threshold where the time to reach convective saturation allows for an effective contrast reduction of the beam intensity driving the instability. This result agrees with three dimensional simulations. Polarization smoothing is shown to double the effective bandwidth.