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| Titel |
Instabilities in a thin current sheet and their consequences |
| VerfasserIn |
N. Singh |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 11, no. 2 ; Nr. 11, no. 2 (2004-04-13), S.153-163 |
| Datensatznummer |
250009128
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| Publikation (Nr.) |
 copernicus.org/npg-11-153-2004.pdf |
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| Zusammenfassung |
| Using a fully 3-D particle in-cell simulation, we studied the electrodynamics of
a thin current sheet (CS). Starting with a uniform plasma and anti-parallel
magnetic field, Harris equilibrium is achieved during the early stage of the
simulation. In the processes of reaching the equilibrium, both electrons and
ions in the newly formed CS are energized and develop pitch-angle anisotropies.
We find two distinct stages of primarily electrostatic instabilities; in the first
stage the relative drift between electrons and ions drives the instability in
the central regions of the CS. The electrostatic fluctuations scatter electrons
causing current disruption in the central region. The associated reduction in
the average drift velocity of the current-carrying electrons generates sheared
flow. The second stage of the instability begins when the drift velocity develops
a minimum in the central plane. Then the shear and the growing electrostatic
fluctuations under the condition of the maintained anti-parallel driving magnetic
field configuration feed each other making the instability explosive. The growing
fluctuations create plasma clumps as the electrons and ions are progressively trapped
in the large-amplitude waves. The density clumping also generates clumps in the
current. The non-uniform current distribution causes magnetic reconnection, accompanied
by heating of electrons and ion at a fast rate and nearly complete bifurcation of
the current sheet. Anomalous resistivity during different stages of the evolution
of the CS is calculated and compared against theory. |
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