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| Titel |
Shear flow instabilities in the earth's plasma sheet region |
| VerfasserIn |
Sunayna Kalra, G. S. Lakhina |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 12, no. 1 ; Nr. 12, no. 1, S.25-32 |
| Datensatznummer |
250010391
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| Publikation (Nr.) |
 copernicus.org/angeo-12-25-1994.pdf |
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| Zusammenfassung |
| Shear flow instability arising from the
velocity shear between the inner and the outer central plasma sheet regions is
studied by treating the plasma as compressible. Based on the linearized MHD
equations, dispersion relations for the surface wave modes occurring at the
boundary of the inner central plasma sheet (ICPS) and the outer central plasma
sheet (OCPS) are derived. The growth rates and the eigenmode frequencies are
obtained numerically. Three data sets consisting of parameters relevant to the
earth's magnetotail are considered. The plasma sheet region is found to be
stable for constant plasma flows unless MA>9.6, where MA
is the Alfvén Mach number in the ICPS. However, for a continuously varying flow
velocity profile in the ICPS, the instability is excited for MA\geq1.4.
The excited modes have oscillation periods of 2-10 min and 1.5-6 s, and typical
transverse wavelengths of 30-100 RE and 0.5-6 RE
for data sets 1 and 2 (i.e., case of no neutral sheet) respectively. For the
data set 3, which corresponds to a neutral sheet at the center of the plasma
sheet, the excited oscillations have periods of 2 s-1 min with transverse
wavelengths of 0.02-1 RE. |
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