Stochastic Acceleration of Electrons by the Right-Hand Extraordinary Mode in the High Density Plasma Region

The resonant acceleration of electrons by the superluminous R-X mode is evaluated in the high density plasma region of Earth, specifically around the geostationary orbit. The corresponding resonant frequency range together with the harmonic N required for producing a significant acceleration is studied in detail. It is found that the stochastic acceleration is basically controlled by the harmonic N and a dimensionless parameter α=|Ω_e²|/ω_pe² (where |Ω_e| and ω_pe are the electron gyrofrequency and plasma frequency respectively). For α= 0.1 (around the geostationary orbit), there are not gyroresonances occurring between electrons and right-hand extraordinary-mode electromagnetic waves until higher harmonics N ≥ 4; while for α= 0.5, the gyroresonance begins at N=2. Substantial acceleration of electrons by the right-hand extraordinary mode is possible for those higher harmonic (N>1) resonances over a wide range of wave normal angles θ. This indicates that higher harmonic resonance can play an important role on the electron acceleration in the high density plasma region (α<1).