Nonlinear mode coupling in pair plasmas

Stark, C.R., Diver, D.A., da Costa, A.A. and Laing, E.W. (2007) Nonlinear mode coupling in pair plasmas. Astronomy and Astrophysics, 476(1), pp. 17-30. (doi: 10.1051/0004-6361:20077988)




Pulsar magnetospheres are composed of electron-positron plasmas characterised by broadband electromagnetic emission, the source of which remains elusive. This paper investigates one possible emission mechanism in which electrostatic oscillations are coupled to propagating electromagnetic waves by the magnetic field inhomogeneity, thus creating a source of radiation in the pulsar magnetosphere. The full nonlinear equations in cylindrical geometry for a streaming cold electron-positron plasma are solved numerically, together with Maxwell's equations, using a Finite-Difference Time Domain method. Electrostatic oscillations are induced in a streaming plasma in the presence of a non-uniform magnetic field, and the resulting electromagnetic waves are modelled self-consistently. Also presented is the linear perturbation analysis of these model equations perturbed from a dynamical equilibrium in order to probe the fundamental modes present in the system. These simulations successfully exhibit the coupling mechanism and the nonlinear interaction between electromagnetic waves and independent plasma oscillations, confirming the importance of coherent plasma effects and collective plasma processes in the pulsar magnetosphere.

Item Type:Articles
Keywords:plasmas, radiation mechanisms: non-thermal, pulsars: general.
Glasgow Author(s) Enlighten ID:da Costa, Professor Antonio and Stark, Mr Craig and Laing, Professor Ernest and Diver, Professor Declan
Authors: Stark, C.R., Diver, D.A., da Costa, A.A., and Laing, E.W.
Subjects:Q Science > QC Physics
Q Science > QA Mathematics
College/School:College of Science and Engineering > School of Physics and Astronomy
Research Group:Astronomy and Astrophysics
Journal Name:Astronomy and Astrophysics
Publisher:EDP Sciences
ISSN (Online):1432-0746
Copyright Holders:Copyright © 2007 EDP Sciences
First Published:First published in Astronomy and Astrophysics 476(1):17-30
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.

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