Reduction of stimulated brillouin scattering by the generation of ion acoustic harmonics

Ion wave harmonics generated by the primary ion acoustic wave excited in stimulated Brillouin scattering are shown to introduce heavy nonlinear damping of the process and to considerably reduce the anomalous reflectivity in an underdense plasma (n/n_c<0.5). The generation of ion wave harmonics acts similarly to strong linear damping and provides an alternative explanation to the heavy damping indicated by experiments.