Backscatter Reduction Using Combined Spatial, Temporal, and Polarization Beam Smoothing in a Long-Scale-length Laser Plasma

Spatial, temporal, and polarization smoothing schemes are combined for the first time to reduce to a few percent the total stimulated backscatter of a NIF-like probe laser beam $(2\times {10}^{15}\mathrm{W}/\mathrm{cm}{}^2,351\mathrm{nm},f/8\mathrm{})$ in a long-scale-length laser plasma. Combining temporal and polarization smoothing reduces simulated Brillouin scattering and simulated Raman scattering (SRS) up to an order of magnitude although neither smoothing scheme by itself is uniformly effective. The results agree with trends observed in simulations performed with the laser-plasma interaction code F3D simulations [R. L. Berger et al., Phys. Plasma 6, 1043 (1999)].