Self-consistent propagation of an electromagnetic wave and power absorption at the electron gyroresonance in a plasma immersed in a non-uniform magnetic field

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Abstract
The self-consistent equation for the propagation of a right-hand polarized electromagnetic wave in a cold plasma immersed in a non-uniform magnetic field is solved exactly under the assumption that the parallel electron velocity v‖ is constant. This equation , which properly takes into account the dissipative component of the induced current, leads to expressions for the reflection, transmission and absorption coefficients which reduce to those obtained by Stix and Budden in the limit v‖ = 0. The reflection coefficient is found to vanish identically, while the absorption is almost complete if the density is sufficiently high. An approximate solution is then obtained for the case where the non-linear effects in the resonance zone (axial acceleration, relativistic change of mass) cannot be neglected. It is found that these effects can give rise to substantial wave reflection. Thus at high h.f. power the electromagnetic energy is effectively coupled to the plasma only if the density is high enough to reduce the intensity of the electric field in the resonance region to a level such that the linear theory applies.