Nonlinear evolutions of large amplitude oblique whistler waves

Abstract

This paper investigates nonlinear evolutions of large amplitude oblique whistler waves (LOWWs) and the interaction with electrons using one-dimensional electromagnetic kinetic simulations. The present research is motivated by recent studies about the nonlinear phenomena of LOWWs. When the propagation angle is not close to the resonance cone angle, the trapping of electrons in the electric potential of LOWWs leads to a moderate damping and a mild acceleration of the electrons via the O'Neil-type damping. In contrast, when the propagation angle of LOWWs is close to the resonance cone angle, the LOWWs undergo a heavy damping accompanied by the stochastic thermalization of the electrons, especially in the perpendicular direction. It is found that the stochastic parameter S, defined by S=16k∥2(eme)Φ0 |J0(k⊥ρ)|ωce2, is a crucial factor determining the damping process. This result demonstrates the importance of self-consistent electron kinetic effects, which are not included in the previous single-particle or fluid approach. The implications of the present findings are discussed.