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Particle drift in the Earth's plasma sheetWe generalize the derivation of the average gradient/curvature-drift for a flux tube filled with an isotropic distribution of particles at specified kinetic energy. The present treatment is restricted to a two-dimensional magnetic field with zero electric field, but it includes all chaotic and Speiser orbits, which do not correspond to the simple picture of gradient/curvature drift. We assume that particles are evenly distributed throughout the regions of phase space allowed by their energy and canonical momentum. This assumption is closely related but not exactly equivalent to the assumption of isotropic pitch-angle distribution. Our derivation assumes that the maximum Larmor radius is small compared to the scale length for equatorial variations in the flux tube volume, but it does not involve any restrictions on the curvature of the field line. The resulting expression for the drift rate is valid for situations where the particle drift velocity is comparable to the thermal speed in some regions. The apparent implication of this generalized treatment is that the existence of very complex non-adiabatic particle trajectories in the plasma sheet may not invalidate previous estimates of the average rate of particle drift out the sides of the tail, estimates that were made under the assumption of simple guiding-center drifts.
Document ID
19930069265
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Wolf, R. A.
(Rice Univ. Houston, TX, United States)
Pontius, D. H., Jr.
(Bartol Research Inst. Newark, DE, United States)
Date Acquired
August 16, 2013
Publication Date
July 23, 1993
Publication Information
Publication: Geophysical Research Letters
Volume: 20
Issue: 14
ISSN: 0094-8276
Subject Category
Geophysics
Accession Number
93A53262
Funding Number(s)
CONTRACT_GRANT: NSF ATM-91-22310
CONTRACT_GRANT: NAG5-1573
CONTRACT_GRANT: NAGW-3474
CONTRACT_GRANT: NAGW-2826
CONTRACT_GRANT: F19628-91-K-0025
Distribution Limits
Public
Copyright
Other

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