Scattering and conversion cross sections in inhomogeneous plasma

A general scattering theory is developed for a magnetic-field-free plasma, allowing for both transverse and longitudinal waves. The four cross sections are derived; they give the scattered components in terms of the frequencies of the incident and scattered waves, and the intensities of the appropriate components in the spectrum of density variations. The theory includes several other scattering formulations as special cases. A number of special features of the cross-section formulas are discussed. The effect of thermal irregularities is considered. Ionosphere ‘incoherent scatter’ experiments, and solar type II and III bursts, are discussed qualitatively.