Absolute Raman Scattering Instabilities in an Inhomogeneous Plasma.

Abstract : The authors derive the equations describing the decay of an intense, coherent EM wave into a scattered EM wave and a plasma wave in an inhomogeneous plasma. The plasma wave becomes nonpropagating in the vicinity of the cut-off of the scattered EM wave. The scattered EM waves can be trapped in the vicinity of their cut-offs and amplified by the pump. The growth rates of the resulting absolute instabilities are computed. These absolute instabilities may explain the strong heating and the blow-off observed in recent computer simulations in the vicinity of the cut-off of backscattered EM waves in Raman scattering. (Author)