Backward Wave Cyclotron-Maser Emission in the Auroral Magnetosphere
Kellett, B. J.; Vorgul, I.; Bingham, R.; Speirs, D. C.; Cairns, R. A.; Phelps, A. D. R.; Ronald, K.
United Kingdom
Abstract
In this Letter, we present theory and particle-in-cell simulations describing cyclotron radio emission from Earth's auroral region and similar phenomena in other astrophysical environments. In particular, we find that the radiation, generated by a down-going electron horseshoe distribution is due to a backward-wave cyclotron-maser emission process. The backward wave nature of the radiation contributes to upward refraction of the radiation that is also enhanced by a density inhomogeneity. We also show that the radiation is preferentially amplified along the auroral oval rather than transversely. The results are in agreement with recent Cluster observations.