Self-consistent treatment of cyclotron resonances in inhomogeneous plasmas

The wave differential operator is obtained directly from the perturbed Vlasov equation for an inhomogeneous equilibrium magnetic field including consistently the effects of strong wave damping and linear mode conversion. In the process, conditions on the parallel wavenumber and the magnetic-field gradient for which such a method is valid are obtained. From these equations it is shown that the inclusion of parameter-gradient terms arising from the spatial dependence of the equilibrium magnetic field is important for accurate calculation of mode conversion from fast to ion-Bernstein wave, although the dispersion-relation-based operator can be sufficient to describe transmission and reflection of the fast wave. Finally, the coupled second-order equations used by Fuchs, V. and Bers, A., Phys. Fluids, 1988, Vol. 31, 3702, are obtained, allowing direct identification of the 'modes' referred to in terms of components of the electric field. By reconciling these two different approaches, some insight is gained into the mode-conversion process. (author)