Particle acceleration by fluctuating electric fields at a magnetic field null point

Petkaki, P. and MacKinnon, A.L. (2007) Particle acceleration by fluctuating electric fields at a magnetic field null point. Astronomy and Astrophysics, 472(2), pp. 623-632. (doi: 10.1051/0004-6361:20066961)

Abstract

<p><b>Context:</b> Particle acceleration consequences from fluctuating electric fields superposed on an X-type magnetic field in collisionless solar plasma are studied. Such a system is chosen to mimic generic features of dynamic reconnection, or the reconnective dissipation of a linear disturbance.</p> <p><b>Aims:</b> We explore numerically the consequences for charged particle distributions of fluctuating electric fields superposed on an X-type magnetic field.</p> <p><b>Methods:</b> Particle distributions are obtained by numerically integrating individual charged particle orbits when a time varying electric field is superimposed on a static X-type neutral point. This configuration represents the effects of the passage of a generic MHD disturbance through such a system. Different frequencies of the electric field are used, representing different possible types of wave. The electric field reduces with increasing distance from the X-type neutral point as in linear dynamic magnetic reconnection.</p> <p><b>Results:</b> The resulting particle distributions have properties that depend on the amplitude and frequency of the electric field. In many cases a bimodal form is found. Depending on the timescale for variation of the electric field, electrons and ions may be accelerated to different degrees and often have energy distributions of different forms. Protons are accelerated to -ray producing energies and electrons to and above hard X-ray producing energies in timescales of 1 s. The acceleration mechanism is possibly important for solar flares and solar noise storms but is also applicable to all collisionless plasmas.</p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacKinnon, Dr Alexander
• Authors: Petkaki, P., and MacKinnon, A.L.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Astronomy and Astrophysics
• Publisher: EDP Sciences
• ISSN: 0004-6361
• ISSN (Online): 1432-0746
• Copyright Holders: Copyright © 2007 EDP Sciences
• First Published: First published in Astronomy and Astrophysics 472(2):623-632
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher