Edge condition and "intrinsic loss" in uniaxial plasma

Abstract

The electromagnetic field behavior near the edge of a conducting wedge in contact with a uniaxial plasma is investigated. The static magnetic field in the plasma is assumed to be perpendicular to the edge. Explicit expressions are obtained for the eigenvalue t which governs the edge behavior. The nonresonance case is treated first and the results are extended subsequently to the resonance case via analytic continuation of the functions involved, using a three-sheeted Riemann surface. The behavior of t is found to be distinctly different in the resonance case from either the isotropic or the nonresonance case in that singularities at the edge now occur for a certain range of the external angle of the conducting wedge, less than π. It is also found that "intrinsic losses" may occur for certain parameters in a purely lossless resonance plasma. However, the degenerate surface wave discussed by earlier workers does not accompany the intrinsic-loss phenomenon as it does for a parallel orientation of the d-c. magnetic field investigated by the above workers. Consequently, it is no longer possible to explain the intrinsic loss in terms of energy transported by the degenerate surface wave. A possible resolution of this difficulty is suggested for an ideally lossless medium via the derivation of a mathematical solution which does not display any intrinsic losses, and hence, satisfies the energy condition in such a system. The slightly lossy case is examined in detail and it is shown that in the presence of some loss in the medium, however slight, large energy losses are expected to occur in the neighborhood of the edge. Nevertheless, these losses are explainable and should not be regarded as "intrinsic".