Stimulated backscattering of electromagnetic waves from electrostatic waves in a magnetized plasma

Abstract

An analysis of the parametric decay of an intense electromagnetic wave into an electrostatic wave and a backscattered electromagnetic wave is presented. A generalized dispersion relation is derived which describes stimulated backscattering from four types of electrostatic waves propagating at an arbitrary angle with respect to a uniform static magnetic field. In the subsequent analysis of the absolute backscatter instability in homogeneous and inhomogeneous, bounded and unbounded plasma, approximations which permit independent treatment of the high-frequency electron modes and the low-frequency ion modes are invoked where appropriate. A numerical study of a laser beam with its direction of propagation making an angle ϑ equal to 5°, 45°, and 85° with the static magnetic field is discussed. Effects of the magnetic field on the growth rate γ0 in an unbounded plasma, the growth rate γ in a bounded plasma, the basic gain length l0, and the inhomogeneity parameter λ are illustrated.