Density fluctuations and the acceleration of electrons by beam-generated langmuir waves in the solar corona

Ratcliffe, H., Bian, N.H. and Kontar, E.P. (2012) Density fluctuations and the acceleration of electrons by beam-generated langmuir waves in the solar corona. Astrophysical Journal, 761(2), p. 176. (doi:10.1088/0004-637X/761/2/176)

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Non-thermal electron populations are observed throughout the heliosphere. The relaxation of an electron beam is known to produce Langmuir waves which, in turn, may substantially modify the electron distribution function. As the Langmuir waves are refracted by background density gradients and as the solar and heliospheric plasma density is naturally perturbed with various levels of inhomogeneity, the interaction of Langmuir waves with non-thermal electrons in inhomogeneous plasmas is an important topic. We investigate the role played by ambient density fluctuations on the beam-plasma relaxation, focusing on the effect of acceleration of beam electrons. The scattering of Langmuir waves off turbulent density fluctuations is modeled as a wavenumber diffusion process which is implemented in numerical simulations of the one-dimensional quasilinear kinetic equations describing the beam relaxation. The results show that a substantial number of beam electrons are accelerated when the diffusive timescale in wavenumber space τ D is of the order of the quasilinear timescale τql, while when τ D Lt τql, the beam relaxation is suppressed. Plasma inhomogeneities are therefore an important means of energy redistribution for waves and hence electrons, and so must be taken into account when interpreting, for example, hard X-ray or Type III emission from flare-accelerated electrons.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Kontar, Professor Eduard and Bian, Dr Nicolas Horace and Ratcliffe, Miss Heather
Authors: Ratcliffe, H., Bian, N.H., and Kontar, E.P.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astrophysical Journal
ISSN (Online):1538-4357
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