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Kinetics of sub-ion scale magnetic holes in the near-Earth plasma sheet

Zhang, X.-J.; Artemyev, A.; Angelopoulos, V.; Horne, R.B.. 2017 Kinetics of sub-ion scale magnetic holes in the near-Earth plasma sheet. Journal of Geophysical Research - Space Physics. 10.1002/2017JA024197

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Abstract/Summary

In collisionless space plasmas, the energy cascade from larger to smaller scales requires effective interactions between ions and electrons. These interactions are organized by sub-ion scale plasma structures in which strong electric fields connect demagnetized ions to magnetized electrons. We consider one such structure, magnetic holes, observed by THEMIS spacecraft in the dipolarized hot plasma sheet. Magnetic holes are localized depressions of the magnetic field with strong currents at their boundaries. Taking advantage of slow plasma convection (∼10 − 20 km/s), we reconstruct the electron velocity distribution within magnetic holes and demonstrate that the current at their boundaries is predominantly carried by magnetized thermal electrons. The motion of these electrons is the combination of diamagnetic drift and E × B drift in a Hall electric field. Magnetic holes can effectively modulate the intensity of electron cyclotron harmonic (ECH) waves, and thus the spatial distribution of thermal electron precipitation. They may also contain field-aligned currents with magnitudes of ∼5 nA/m2(one order of magnitude smaller than the cross-field current density). Therefore, sub-ion scale magnetic holes can be important for ionosphere-magnetosphere coupling.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1002/2017JA024197
Programmes: BAS Programmes > BAS Programmes 2015 > Space Weather and Atmosphere
Additional Keywords: magnetic holes, plasma sheet, sub-ion scale structures, field-aligned currents, ECH waves, electron precipitation
Date made live: 05 Sep 2017 13:17 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/516713

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