Parametric scattering in electron-cyclotron resonance heating

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Abstract
The problem of parametric scattering of the extraordinary and ordinary waves near electron‐cyclotron frequency off ion‐cyclotron waves is investigated. Convective thresholds for an inhomogeneous plasma are obtained analytically in the case when the scattered ordinary or extraordinary waves and the ion‐cyclotron wave are weakly damped. There are no restrictions on the angles the waves make with the ambient magnetic field. The dependence of the thresholds on the plasma density, electron and ion temperatures, and propagation angles is described. It is found that in present‐day electron‐cyclotron resonance heating experiments (I≲1 kW/cm2) the thresholds are evidently too high for parametric scattering, but in high‐intensity (I≳10 kW/cm2) experiments the possibility for scattering exists.