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On the radial force balance in the quiet time magnetotail current sheet
Author(s) -
Artemyev A. V.,
Angelopoulos V.,
Runov A.
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja022480
Subject(s) - physics , current sheet , pressure gradient force , radius , current (fluid) , isotropy , mechanics , magnetic field , pressure gradient , anisotropy , plasma sheet , tension (geology) , current density , classical mechanics , magnetosphere , atomic physics , magnetohydrodynamics , optics , thermodynamics , quantum mechanics , computer security , computer science , moment (physics)
Using Time History of Events and Macroscale Interactions spacecraft observations of the quite magnetotail current sheet within the r ∈[9,35] R E region ( r is the radial distance from Earth and R E is Earth's radius), we investigate the thermal plasma pressure distribution along the magnetotail. Taking advantage of flapping motions of an ensemble of current sheets at various distances, we estimate the current density magnitude j y (in GSM coordinates). Comparing the tension force j y B z ( B z is the magnetic field component) with the radial gradient of the plasma pressure demonstrates that this gradient is only a small fraction, ∼10–15%, of the Ampere force exerted on the cross‐tail current, in the r > 15 R E region. We also estimate the contribution of the electron temperature anisotropy to the pressure balance: in the r > 15 R E region the corresponding force can balance only 10–15% of the observed tension force j y B z . Thus, we conclude that about 70% of the tension force is not balanced by the combination of isotropic radial pressure gradient or the electron anisotropy. We discuss mechanisms that could be responsible for balancing the magnetotail current sheet.