Modeling of stimulated Brillouin scattering near the critical-density surface in the plasmas of direct-drive inertial confinement fusion targets

The nonlinear propagation of laser beams, smoothed by spatial and temporal bandwidth, near the critical density surface of direct-drive inertial confinement fusion targets has been modeled. The interplay between filamentation and forward and backward stimulated Brillouin scattering (SBS) is described in the presence of light reflected from the critical density surface and high absorption of light near the critical density. The spectrum of backscattered light develops a red shift due to SBS, which can be seeded by the reflection of light from the critical surface. The intensity of backscattered light decreases moderately as the bandwidth of smoothing by spectral dispersion is increased. (C) 2004 American Institute of Physics.