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| Titel |
Shear flow instabilities in the Earth's magnetotail |
| VerfasserIn |
R. V. Reddy, 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 ; 14, no. 8 ; Nr. 14, no. 8, S.786-793 |
| Datensatznummer |
250012381
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| Publikation (Nr.) |
 copernicus.org/angeo-14-786-1996.pdf |
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| Zusammenfassung |
| Shear flow instability is studied in the
Earth's magnetotail by treating plasma as compressible. A dispersion relation is
derived from the linearized MHD equations using the oscillating boundary
conditions at the inner central plasma sheet/outer central plasma sheet (OCPS)
interface and OCPS/plasma-sheet boundary layer (PSBL) interface, whereas the
surface-mode boundary condition is used at the PSBL/lobe interface. The growth
rates and the real frequencies are obtained numerically for near-Earth (∣X∣~10–15
RE) and far-Earth (∣X∣~100 RE)
magnetotail parameters. The periods and wavelengths of excited modes depend
sensitively on the value of plasma-sheet half thickness, L, which is
taken as L=5 RE for quiet time and L=1 RE
for disturbed time. The plasma-sheet region is found to be stable for constant
plasma flows unless MA3>1.25, where MA3
is the Alfvén Mach number in PSBL. For near-Earth magnetotail, the excited
oscillations have periods of 2–20 min (quiet time) and 0.5–4 min (disturbed
time) with typical transverse wavelengths of 2–30 RE and
0.5–6.5 RE, respectively; whereas for distant magnetotail, the
analysis predicts the oscillation periods of ~8–80 min for quiet periods and
2–16 min for disturbed periods. |
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