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Magnetosheath-ionspheric plasma interactions in the cusp/cleft. 2: Mesoscale particle simulationsIonospheric plasma flowing out from the cusp can be an important source of plasma to the magnetosphere. One source of free energy that can drive this outflow is the injection of magnetosheath plasma into the cusp. Two-dimensional (three velocity) mesoscale particle simulations are used to investigate the particle dynamics in the cusp during southward interplanetary magnetic field. This mesoscale model self-consistently incorporates (1) global influences such as the convection of plasma across the cusp, the action of the mirror force, and the injection of the magnetosheath plasma, and (2) wave-particle interactions which produce the actual coupling between the magnetosheath and ionospheric plasmas. It is shown that, because the thermal speed of the electrons is higher than the bulk motion of the magnetosheath plasma, an upward current is formed on the equatorward edge of the injection region with return currents on either side. However, the poleward return currents are the stronger due to the convection and mirroring of many of the magnetosheath electrons. The electron distribution in this latter region evolves from upward directed streams to single-sided loss cones or possibly electron conics. The ion distribution also shows a variety of distinct features that are produced by spatial and/or temporal effects associated with varying convection patterns and wave-particle interactions. On the equatorward edge the distribution has a downflowing magnetosheath component and an upflowing cold ionospheric component due to continuous convection of ionospheric plasma into the region. In the center of the magnetosheath region, heating from the development of an ion-ion streaming instability causes the suppression of the cold ionospheric component and the formation of downward ionospheric streams. Further poleward there is velocity filtering of ions with low pitch angles, so that the magnetosheath ions develop a ring-beam distribution and the ensuing wave instabilities generate downward ionospheric conics. These downward ionospheric components are eventually turned by the mirror force, leading to the production of upward conics at elevated energies throughout the region.
Document ID
19950059018
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Winglee, R. M.
(Univ. of Washington, Seattle, WA United States)
Menietti, J. D.
(Univ. of Iowa, Iowa City, IA United States)
Lin, C. S.
(Southwest Research Inst. San Antonio, TX, United States)
Date Acquired
August 16, 2013
Publication Date
November 1, 1993
Publication Information
Publication: Journal of Geophysical Research
Volume: 98
Issue: A11
ISSN: 0148-0227
Subject Category
Astrophysics
Accession Number
95A90617
Funding Number(s)
CONTRACT_GRANT: NAGW-1936
CONTRACT_GRANT: NAGW-2412
CONTRACT_GRANT: NSF ATM-92-96075
CONTRACT_GRANT: NAGW-2471
Distribution Limits
Public
Copyright
Other

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