Theory of electron cyclotron absorption of magnetized plasmas

Abstract

A comprehensive overview of the theory of the absorption of electromagnetic waves around the electron cyclotron frequency and its harmonics in a weakly relativistic Maxwellian plasma of finite density is given for propagation both oblique and perpendicular with respect to a static magnetic field. Particular stress is laid on the physics involved in the absorption process rather than on the detailed derivation of the formulae. The absorption coefficient is evaluated on the basis of the energy balance which displays the significance of polarization effects related to finite plasma density. Furthermore, the optical thickness of a Tokamak plasma for the various harmonics of the two fundamental modes is given and the corresponding scaling with respect to the plasma parameters and magnetic field is examined.