Resonant Acceleration of Magnetospheric Electrons Driven bythe R–X Mode

Abstract

An extended relativistic model is developed to evaluate thesuperluminous R–X-mode resonance especially the second-order andthird-order resonances with electrons in the Earth's magnetosphere. Thepotential for stochastic electron acceleration driven by the R–X modeis determined by the dispersive properties of the R–X mode andspecifically the resonant harmonic N. In contrast to the limitedacceleration at the first harmonic (N = 1) resonance, for the higherharmonic (N>1) resonances, the R–X mode is capable of acceleratingelectrons from ~10 keV to ~ MeV energies, over a wide rangeof wave normal angles, in spatial regions extending from the auroralcavity to the latitude (>30 degrees) outer radiation belt. Thisindicates that higher-order resonance is essentially important forthe electron acceleration for the oblique wave propagation.