Effect of B{sub y} on neutral line ridges and dynamical source ordering

Journal Article · Thu Dec 01 04:00:00 EST 1994 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/94JA01770· OSTI ID:91336

Martin, Jr, R F; Klamczynski, K ^[1]; Speiser, T W ^[2]

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1. Illinois State Univ., Normal, IL (United States)
2. Univ. of Colorado, Boulder, CO (United States)

In this paper the authors study the effect of a uniform magnetic field B{sub y} in the cross-tail y direction on the dynamics and distribution function of energetic ions in a current sheet model including a neutral line. Martin and Speiser have previously shown that a {open_quotes}ridge{close_quotes} in the velocity space distribution function is a remote neutral line signature in a two-dimensional field without B{sub y}. These 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 B{sub z}) 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 new neutral line signatures which depend strongly on whether the observation point is above or below the current sheet. These results are used to estimate B{sub y} < 2 nT is the AMPTE/IRM event modeled by Speiser and Martin, which is consistent with onboard magnetometer measurements. The authors further show that the cause of the new structures appearing at large B{sub y} is the same source separation effect that produced the original ridge and that all these signatures are relatively insensitive to a small parallel electric field. Finally, they point out a dynamical ordering which occurs at large B{sub y}: Using high-resolution simulations, they 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. 321 refs., 14 figs.

• OSTI ID: 91336
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A12 Vol. 99; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DISTRIBUTION FUNCTIONS
DYNAMICS
MAGNETIC FIELD REVERSAL
MAGNETOTAIL
REMOTE SENSING
TAIL IONS