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| Titel |
Nonlinear equilibrium structure of thin currents sheets: influence of electron pressure anisotropy |
| VerfasserIn |
L. M. Zelenyi, H. V. Malova, V. Yu. Popov, D. Delcourt, A. S. Sharma |
| 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. 5/6 ; Nr. 11, no. 5/6 (2004-11-23), S.579-587 |
| Datensatznummer |
250008988
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| Publikation (Nr.) |
 copernicus.org/npg-11-579-2004.pdf |
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| Zusammenfassung |
| Thin current sheets represent important and puzzling sites of magnetic
energy storage and subsequent fast release. Such structures are observed in
planetary magnetospheres, solar atmosphere and are expected to be widespread
in nature. The thin current sheet structure resembles a collapsing MHD
solution with a plane singularity. Being potential sites of effective energy
accumulation, these structures have received a good deal of attention during
the last decade, especially after the launch of the multiprobe CLUSTER
mission which is capable of resolving their 3D features. Many theoretical
models of thin current sheet dynamics, including the well-known current
sheet bifurcation, have been developed recently. A self-consistent 1D
analytical model of thin current sheets in which the tension of the magnetic
field lines is balanced by the ion inertia rather than by the plasma
pressure gradients was developed earlier. The influence of the anisotropic
electron population and of the corresponding electrostatic field that acts
to restore quasi-neutrality of the plasma is taken into account. It is
assumed that the electron motion is fluid-like in the direction
perpendicular to the magnetic field and fast enough to support
quasi-equilibrium Boltzmann distribution along the field lines.
Electrostatic effects lead to an interesting feature of the current density
profile inside the current sheet, i.e. a narrow sharp peak of electron
current in the very center of the sheet due to fast curvature drift of the
particles in this region. The corresponding magnetic field profile becomes
much steeper near the neutral plane although the total cross-tail current is
in all cases dominated by the ion contribution. The dependence of
electrostatic effects on the ion to electron temperature ratio, the
curvature of the magnetic field lines, and the average electron magnetic
moment is also analyzed. The implications of these effects on the fine
structure of thin current sheets and their potential impact on substorm
dynamics are presented. |
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