Wave emission from mode conversion regions

An important feature of nonuniform media is the possibility of linear mode conversion due to the near-degeneracy of the dispersion relations of two wave modes in localized regions of the plasma. Wave emission from mode conversion regions has been a subject of a discussion in several recent publications (see, e.g. Swanson, Rev. Mod. Phys. 64, 837 (1995)). Here we present a new approach to this problem which is based on the ray tracing technique of Tracy et al., Phys. Plasmas 2, 4413 (1995), extended to mode conversion regions, as discussed in Friedland and Kaufman, Phys. Fluids 30, 3050 (1987). This extension allows one to connect the local wave field emitted by a source to rays outgoing from the conversion region. The analysis is performed for both positive-and negative-energy waves in arbitrary dimensions.