Enhanced incoherent scattering at the upper-hybrid resonance. I. Cold plasma theory

Incoherent scattering of microwaves at the upper-hybrid resonance in an inhomogeneous plane-layered plasma is investigated. The incident and scattered waves propagate in the plane characterized by the directions of the density gradient and the externally imposed magnetic field. The frequency of the waves is close to the cyclotron frequency and therefore full account of the dispersive properties of the plasma is taken. The principal aim of the study is the investigation of collective effects on the scattered flux of energy in a toroidal machine and therefore the case of accessible resonance and frequency shift of the order of the ion frequency are specificallly considered. Except in the spectrum of the density fluctuations, thermal effects are neglected. This is the collision-dominated case. The relevant equations are solved for the case of opaque plasma and the scattered flux of energy is estimated. The result obtained indicates that enhancement of the scattering cross section with respect to the transparent scattering is expected for ν/ω ≪ 1, where ν is the electron collision frequency.