Cluster observations on the thin current sheet in the magnetotail
A magnetotail event on 15 September 2001 is analyzed, during which the Cluster spacecraft observed both embedding and bifurcation of the Thin Current Sheet (TCS). It is indicated that the ion anisotropy and nongyrotropy are responsible for those new equilibrium features that represent deviations...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2008-05-01
|
| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/26/929/2008/angeo-26-929-2008.pdf |
| Summary: | A magnetotail event on 15 September 2001 is analyzed, during which the
Cluster spacecraft observed both embedding and bifurcation of the Thin
Current Sheet (TCS). It is indicated that the ion anisotropy and
nongyrotropy are responsible for those new equilibrium features that
represent deviations from the conventional Harris model. Measurements show
that an embedded proton TCS manifests a pressure anisotropy with <I>p</I><sub>||</sub>><I>p</I><sub>⊥</sub>, simultaneously associated with a density embedding; while
a bifurcated oxygen ion TCS exhibits a pressure anisotropy mainly with
<I>p</I><sub>||</sub><<I>p</I><sub>⊥</sub> and nongrotropy, except at the edges where <I>p</I><sub>||</sub>><I>p</I><sub>⊥</sub> is the necessary marginal firehose stability condition. The
local flapping motion of the TCS was observed, and some particular features
such as the solitary wave-like behavior and the kink motion in the plane
perpendicular to the Sun-Earth direction were revealed. The present
investigation intimates the complexity of equilibria of the magnetotail current
sheet and declares the crucial role played by the ion kinetics in the
dynamics of TCSs. |
|---|---|
| ISSN: | 0992-7689 1432-0576 |