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| Titel |
Energy-dispersed ions in the plasma sheet boundary layer and associated phenomena: Ion heating, electron acceleration, Alfvén waves, broadband waves, perpendicular electric field spikes, and auroral emissions |
| VerfasserIn |
A. Keiling, G. K. Parks, H. Rème, I. Dandouras, M. Wilber, L. Kistler, C. Owen, A. N. Fazakerley, E. Lucek, M. Maksimovic, N. Cornilleau-Wehrlin |
| 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 ; 24, no. 10 ; Nr. 24, no. 10 (2006-10-20), S.2685-2707 |
| Datensatznummer |
250015658
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| Publikation (Nr.) |
 copernicus.org/angeo-24-2685-2006.pdf |
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| Zusammenfassung |
| Recent Cluster studies reported properties of multiple
energy-dispersed ion structures in the plasma sheet boundary layer (PSBL)
that showed substructure with several well separated ion beamlets, covering
energies from 3 keV up to 100 keV (Keiling et al., 2004a, b). Here we
report observations from two PSBL crossings, which show a number of
identified one-to-one correlations between this beamlet substructure and
several plasma-field characteristics: (a) bimodal ion conics (<1 keV), (b)
field-aligned electron flow (<1 keV), (c) perpendicular electric field
spikes (~20 mV/m), (d) broadband electrostatic ELF wave packets
(<12.5 Hz), and (e) enhanced broadband electromagnetic waves (<4 kHz).
The one-to-one correlations strongly suggest that these phenomena were
energetically driven by the ion beamlets, also noting that the energy flux
of the ion beamlets was 1–2 orders of magnitude larger than, for example,
the energy flux of the ion outflow. In addition, several more loosely
associated correspondences were observed within the extended region
containing the beamlets: (f) electrostatic waves (BEN) (up to 4 kHz), (g)
traveling and standing ULF Alfvén waves, (h) field-aligned currents
(FAC), and (i) auroral emissions on conjugate magnetic field lines. Possible
generation scenarios for these phenomena are discussed. In conclusion, it is
argued that the free energy of magnetotail ion beamlets drove a variety of
phenomena and that the spatial fine structure of the beamlets dictated the
locations of where some of these phenomena occurred. This emphasizes the
notion that PSBL ion beams are important for magnetosphere-ionosphere
coupling. However, it is also shown that the dissipation of electromagnetic
energy flux (at altitudes below Cluster) of the simultaneously occurring
Alfvén waves and FAC was larger (FAC being the largest) than the
dissipation of beam kinetic energy flux, and thus these two energy carriers
contributed more to the energy transport on PSBL field lines from the
distant magnetotail to the ionosphere than the ion beams. |
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