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| Titel |
Large-scale fluctuations of PSBL magnetic flux tubes induced by the field-aligned motion of highly accelerated ions |
| VerfasserIn |
E. E. Grigorenko, T. M. Burinskaya, M. Shevelev, J.-A. Sauvaud, L. M. Zelenyi |
| 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 ; 28, no. 6 ; Nr. 28, no. 6 (2010-06-11), S.1273-1288 |
| Datensatznummer |
250016843
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| Publikation (Nr.) |
 copernicus.org/angeo-28-1273-2010.pdf |
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| Zusammenfassung |
| We present a comprehensive analysis of magnetic field and plasma data
measured in the course of 170 crossings of the lobeward edge of Plasma Sheet
Boundary Layer (PSBL) in the Earth's magnetotail by Cluster spacecraft. We
found that large-scale fluctuations of the magnetic flux tubes have been
registered during intervals of propagation of high velocity field-aligned
ions. The observed kink-like oscillations propagate earthward along the main
magnetic field with phase velocities of the order of local Alfvén
velocity and have typical wavelengths ~5–20 RE, and frequencies of
the order of 0.004–0.02 Hz. The oscillations of PSBL magnetic flux tubes
are manifested also in a sudden increase of drift velocity of cold lobe ions
streaming tailward. Since in the majority of PSBL crossings in our data set,
the densities of currents corresponding to electron-ion relative drift have
been low, the investigation of Kelvin-Helmholtz (K-H) instability in a
bounded flow sandwiched between the plasma sheet and the lobe has been
performed to analyze its relevance to generation of the observed ultra-low
frequency oscillations with wavelengths much larger than the flow width. The
calculations have shown that, when plasma conditions are favorable for the
excitation of K-H instability at least at one of the flow boundaries,
kink-like ultra-low frequency waves, resembling the experimentally observed
ones, could become unstable and efficiently develop in the system. |
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