Phase mixing of shear Alfven waves as a new mechanism for electron acceleration in collisionless, kinetic plasmas

Abstract

Particle-In-Cell (kinetic) simulations of shear Alfv\'en wave interaction with one dimensional, across the uniform magnetic field, density inhomogeneity (phase mixing) in collisionless plasma were performed for the first time. As a result a new electron acceleration mechanism is discovered. Progressive distortion of Alfv\'en wave front, due to the differences in local Alfv\'en speed, generates nearly parallel to the magnetic field electrostatic fields, which accelerate electrons via Landau damping. Surprisingly, amplitude decay law in the inhomogeneous regions, in the kinetic regime, is the same as in the MHD approximation described by Heyvaerts and Priest (1983).