Suppression of reflected electrons by kinetic Alfvén turbulence in a quasi-perpendicular shock: Particle-in-cell simulations

Abstract

Shock drift acceleration is one of the important mechanisms for electron acceleration associated with magnetic mirror reflection along the magnetic field in a quasi-perpendicular collisionless shock. We study the influence of a rippled shock surface in the in-plane magnetic field on the magnetic mirror reflection of electrons. Simulation results show that the number of reflected electrons reduces after generation of the rippled shock surface. Electric and magnetic wavenumber spectra of the generated fluctuations in the shock transition region indicate the existence of kinetic Alfvén turbulence. The kinetic Alfvén turbulence decreases the electron pitch angle by parallel scattering, which reduces the magnetic mirror force acting on the electrons. These results suggest that the shock-generated kinetic Alfvén turbulence suppresses the magnetic mirror reflection of electrons during the shock drift acceleration. © 2011. The American Astronomical Society. All rights reserved.