Ion temperature anisotropy across a magnetotail reconnection jet
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Published version
Author(s)
Hietala, H
Drake, JF
Phan, TD
Eastwood, J
McFadden, JP
Type
Journal Article
Abstract
A significant fraction of the energy released by magnetotail reconnection appears to go into ion heating, but this heating is generally anisotropic. We examine ARTEMIS dual-spacecraft observations of a long-duration magnetotail exhaust generated by anti-parallel reconnection in conjunction with Particle-In-Cell simulations, showing spatial variations in the anisotropy across the outflow far (> 100di) downstream of the X-line. A consistent pattern is found in both the spacecraft data and the simulations: Whilst the total temperature across the exhaust is rather constant, near the boundaries Ti,|| dominates. The plasma is well-above the firehose threshold within patchy spatial regions at |BX| ∈ [0.1, 0.5]B0, suggesting that the drive for the instability is strong and the instability is too weak to relax the anisotropy. At the mid-plane (|BX|0.1 B0), Ti,⊥ > Ti,|| and ions undergo Speiser-like motion despite the large distance from the X-line.
Date Issued
2015-09-28
Date Acceptance
2015-08-19
Citation
Geophysical Research Letters, 2015, 42 (18), pp.7239-7247
ISSN
1944-8007
Publisher
American Geophysical Union (AGU)
Start Page
7239
End Page
7247
Journal / Book Title
Geophysical Research Letters
Volume
42
Issue
18
Copyright Statement
© 2015. The Authors.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Sponsor
Imperial College Trust
Commission of the European Communities
Science and Technology Facilities Council (STFC)
Science and Technology Facilities Council [2006-2012]
Grant Number
N/A
269297
ST/K001051/1
ST/K001051/1
Subjects
Science & Technology
Physical Sciences
Geosciences, Multidisciplinary
Geology
magnetic reconnection
magnetotail
temperature anisotropy
ion heating
MAGNETIC RECONNECTION
PLASMA SHEET
PRESSURE ANISOTROPY
SIMULATIONS
DYNAMICS
SPEED
ion heating
magnetic reconnection
magnetotail
temperature anisotropy
Meteorology & Atmospheric Sciences
Publication Status
Published
Date Publish Online
2015-08-24