Parallel electric field amplification by phase mixing of Alfven waves

Department of Physics & Astronomy, University of Glasgow, G12 8QQ, UK
e-mail: nbian@astro.gla.ac.uk

Received: 13 July 2010
Accepted: 10 November 2010

Abstract

Context. Several numerical studies have identified phase mixing of low-frequency Alfven waves as a means of parallel electric field amplification and acceleration of electrons in a collisionless plasma.

Aims. Theoretical explanations are given of how phase mixing amplifies the parallel electric field and, as a consequence, also leads to enhanced collisionless damping of the wave by energy transfer to the electrons.

Methods. Our results are based on the properties of the Alfven waves in a warm plasma. These results are obtained within the framework of drift-kinetic theory.

Results. Phase mixing in a collisionless low-β plasma proceeds in a manner very similar to the resistive case, except that electron Landau damping is the primary energy dissipation channel. The time and length scales involved are evaluated. We also focus on the evolution of the parallel electric field and calculate its maximum value in the course of its amplification