The effect of induced spatial incoherence on the absolute Raman instability

Abstract
A numerical and analytical study of the Raman instability in a homogeneous plasma is presented in which the pump has been modeled to include the effects of broad bandwidth and the induced spatial incoherence (ISI) method of beam smoothing. For a time‐averaged homogeneous growth rate γ̄0 and a bandwidth σ, there is a significant reduction in Raman backscattering when σ≳2γ0, for γ̄20 near threshold intensity. However, for γ̄20 very large compared to the threshold, neither ISI nor bandwidth affects Raman scattering.