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Effect of B(sub y) on neutral line ridges and dynamical source orderingIn this paper we study the effect of a uniform magnetic field B(sub y) in the cross-tail y direction on the dynamics and distribution of energetic ions in a current sheet model including a neutral line. Martin and Speiser (1988) have previously shown that a 'ridge' in the velocity space distribution function is a remote neutral line signature in a two-dimensional field without B(sub y). Our results show that as B(sub y) is increased, using nominal tail parameters, there is very little change in the ridge signature for small B(sub y) (up to about 4 times B(sub z)). For intermediate values (up to about 10 times times B(sub Y)) the ridge becomes observable further from the neutral line, while close to the X line the ridge is strongly modified. For large B(sub y) (of the order of B(sub x)) the ridge evolves into the new neutral line signatures which depend strongly on whether the observations point is above or below the current sheet. These results are used to estimate B(sub y) less than 2 nT in the Active Magentospheric Particle Traces Explorers/Ion Release Module (AMPTE/IRM) event modeled by Speiser and Martin (1994), which is consistent with onboard magnetometer measurements. We further show that the cause of the new structures appearing at large B(sub Y) is the same source seperation effect that produced the original ridge and that all these signatures are relatively insensitive to a small parallel electric field. Finally, we point our a dynamical ordering which occurs at large B(sub y): Using high-resolution simulations, we find a common boundary separating regions of positive and negative initial x, y, and z position, as well as initial pitch angle. This boundary is purely dynamical in nature and is independent of modeled source distributions.
Document ID
19950048214
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Martin, R. F., Jr.
(Illinois State Univ. Normal, IL, Us, United States)
Speiser, T. W.
(Univ. of Colorado, Boulder, CO United States)
Klamczynski, K.
(Illinois State Univ. Normal, IL, Us, United States)
Date Acquired
August 16, 2013
Publication Date
December 1, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: A12
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
95A79813
Funding Number(s)
CONTRACT_GRANT: NAGW-2968
CONTRACT_GRANT: NAG5-1506
CONTRACT_GRANT: NAGW-1176
CONTRACT_GRANT: NSF ATM-93-01801
CONTRACT_GRANT: NSF ATM-91-12954
CONTRACT_GRANT: NSF ATM-90-02447
Distribution Limits
Public
Copyright
Other

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