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Plasma electrons in Saturn's magnetotail: structure, distribution and energisation

Arridge, Chris S. and McAndrews, H.J. and Jackman, C.M. and Forsyth, C. and Walsh, A.P. and Sittler, E.C. and Gilbert, Linda K. and Lewis, Gethyn R. and Russell, C.T. and Coates, Andrew J. and Dougherty, M.K. and Collinson, G.A. and Wellbrock, Anne and Young, D.T. (2009) Plasma electrons in Saturn's magnetotail: structure, distribution and energisation. Planetary and Space Science 57 (14-15), pp. 2032-2047. ISSN 0032-0633.

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Official URL: http://dx.doi.org/10.1016/j.pss.2009.09.007

Abstract

In this paper Saturn's nightside and pre-dawn electron (0.5 eV–28 keV) plasma sheet is studied using Cassini plasma electron and magnetic field data from 2006. Case studies are presented which exemplify the typical and atypical states of the plasma sheet, and are complemented by a statistical study of the plasma sheet. It will be shown that Saturn's nightside and pre-dawn electron plasma sheet exists in two states: a quiescent state with a steady electron temperature of View the MathML source and where the electron distribution functions are best characterised by Kappa distributions, and a disturbed state where the electrons are hot View the MathML source and often seen in alternating layers between warm and hot populations. Evidence is also presented for bimodal cold/warm (both quiet and disturbed states) and warm/hot distributions (disturbed states). The disturbed states are qualitatively similar to electron distributions from Earth's magnetotail during intervals of reconnection and we argue that these disturbed states also result from periods of tail reconnection. We present statistics of electron number density, temperature, partial electron beta, and pressure, and show that large values of partial beta are necessary but not sufficient to uniquely identify the central plasma sheet. Finally the thermodynamic properties of the electron plasma sheet are studied and we show that the electrons behave isothermally. These results are important for modelling and theoretical analyses, and for use in studies which examine dynamics in Saturn's magnetosphere.

Item Type: Article
Keyword(s) / Subject(s): Cassini, Magnetotail, plasma sheet, electrons
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Earth and Planetary Sciences > UCL/Birkbeck Centre for Planetary Sciences
Depositing User: Administrator
Date Deposited: 27 Jul 2011 11:31
Last Modified: 17 Apr 2013 12:21
URI: http://eprints.bbk.ac.uk/id/eprint/3881

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