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Influence of the interplanetary magnetic field orientation on polar cap ion trajectories - Energy gain and drift effectsThe influence of the interplanetary magnetic field (IMF) orientation on the transport of low-energy ions injected from the ionosphere is investigated using three-dimensional particle codes. It is shown that, unlike the auroral zone outflow, the ions originating from the polar cap region exhibit drastically different drift paths during southward and northward IMF. During southward IMF orientation, a 'two-cell' convection pattern prevails in the ionosphere, and three-dimensional simulations of ion trajectories indicate a preferential trapping of the light ions H(+) in the central plasma sheet, due to the wide azimuthal dispersion of the heavy ions, O(+). In contrast, for northward IMF orientation, the 'four-cell' potential distribution predicted in the ionosphere imposes a temporary ion drift toward higher L shells in the central polar cap. In this case, while the light ions can escape into the magnetotail, the heavy ions can remain trapped, featuring more intense acceleration (from a few electron volts up to the keV range) followed by precipitation at high invariant latitudes, as a consequence of their further travel into the tail.
Document ID
19880059429
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Delcourt, D. C.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Horwitz, J. L.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Swinney, K. R.
(Alabama, University Huntsville, United States)
Date Acquired
August 13, 2013
Publication Date
July 1, 1988
Publication Information
Publication: Journal of Geophysical Research
Volume: 93
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
88A46656
Funding Number(s)
CONTRACT_GRANT: NAG8-58
CONTRACT_GRANT: NGT-01-008-804
CONTRACT_GRANT: NSF ATM-85-03102
Distribution Limits
Public
Copyright
Other

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