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The particle carriers of field‐aligned currents in the Earth's magnetotail during a substorm
Author(s) -
Cheng Z. W.,
Zhang J. C.,
Shi J. K.,
Kistler L. M.,
Dunlop M.,
Dandouras I.,
Fazakerley 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 - 10.1002/2015ja022071
Subject(s) - substorm , plasma sheet , physics , magnetosphere , ionosphere , electron , geophysics , outflow , earth's magnetic field , plasma , solar wind , range (aeronautics) , atomic physics , magnetic field , materials science , meteorology , quantum mechanics , composite material
Although the particle carriers of field‐aligned currents (FACs) in the Earth's magnetotail play an important role in the transfer of momentum and energy between the solar wind, magnetosphere, and ionosphere, the characteristics of the FAC carriers have been poorly understood. Taking advantage of multiinstrument magnetic field and plasma data collected by the four spacecraft of the Cluster constellation as they traversed the northern plasma sheet boundary layer in the magnetotail on 14 September 2004, we identified the species type and energy range of the FAC carriers for the first time. The results indicate that part of tailward FACs is carried by energetic keV ions, which are probably originated from the ionosphere through outflow, and they are not too small (~2 nA/m 2 ) to be ignored. The earthward (tailward) FACs are mainly carried by the dominant tailward (earthward) motion of electrons, and higher‐energy electrons (from ~0.5 to 26 keV) are the main carriers.