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Proton and helium cyclotron anisotropy instability thresholds in the magnetosheathBoth the protons and the helium ions of the terrestrial magnetosheath typically display T (sub perpendicular) greater than T (sub parallel), where perpendicular to and parallel to denote directions perpendicular and parallel to the background magnetic field. Observations of the highly compressed magnetosheath show an inverse correlation between these ion temperature anisotropies and the parallel proton beta. Computer simulations have demonstrated that these correlations are due to wave-particle scattering by electromagnetic ion cyclotron anisotropy instabilities. These correlations correspond to linear theory thresholds of the proton cyclotron and the helium cyclotron instabilities. This paper uses linear Vlasov theory and the assumption of a constant maximum growth rate to obtain closed-form expressions for these thresholds as a function of the relative helium density and the parallel proton beta in a parameter model of the magnetosheath.
Document ID
19950029550
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Gary, S. Peter
(Los Alamos National Laboratory, Los Alamos, NM United States)
Convery, Patrick D.
(Los Alamos National Laboratory, Los Alamos, NM United States)
Denton, Richard E.
(Dartmouth College, Hanover, NH United States)
Fuselier, Stephen A.
(Lockheed Palo Alto Research Laboratory, Palo Alto, CA United States)
Anderson, Brian J.
(Johns Hopkins Univ. Laurel, MD, United States)
Date Acquired
August 16, 2013
Publication Date
April 1, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: A4
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
95A61149
Funding Number(s)
CONTRACT_GRANT: NAGW-1652
CONTRACT_GRANT: NAGW-3052
CONTRACT_GRANT: NAS5-30565
Distribution Limits
Public
Copyright
Other

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