Large-amplitude oblique whistler waves and relativisitc electron acceleration

Summary form only given. Observation shows that large-amplitude whistler waves propagating in oblique directions with respect to the ambient magnetic field may be responsible for energizing the radiation belt electrons to relativistic energies within a time scale as short as a fraction of a second. Test-particle simulations available in the literature invariably adopt simple model waveforms for t he oblique whistlers. Solutions of fully nonlinear warm electron fluid equation show that oblique whistlers not only undergo steepening but also large-amplitude whistlers are unstable t o nonlinear decay instability. The physics of whistler wave steepening and nonlinear decay processes as well as their impact on particle interaction will be discussed. Relativistic test particle simulation shows that a population of initially low energy electrons can be accelerated in a few seconds to O(10) Me V energies. However, it is shown that such an efficient electr on acceleration is possible only if the wave propagation angle is sufficiently large and that quasi-parallel propagation of whistler waves cannot accelerate the electrons.