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Cluster observations of plasma in the high latitude magnetotail associated with cusp-aligned arcs
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  • Michaela Kerry Mooney,
  • Stephen Milan,
  • Mark Lester,
  • Iannis S Dandouras,
  • Christopher M. Carr,
  • Andrew N. Fazakerley
Michaela Kerry Mooney
University of Leicester

Corresponding Author:[email protected]

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Stephen Milan
University of Leicester
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Mark Lester
University of Leicester
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Iannis S Dandouras
Institut de Recherche en Astrophysique et Planétologie, UPS-CNRS Toulouse, France
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Christopher M. Carr
Imperial College
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Andrew N. Fazakerley
University College London
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Abstract

During periods of northward interplanetary magnetic field (IMF), the magnetospheric structure and dynamics are dramatically different compared to the southward IMF case. Previous studies using both observations and simulations have shown that the magnetotail becomes dominated by closed magnetic flux and associated trapped particle populations. In this study, we analyse three intervals of plasma observed in the high latitude magnetotail during a period of prolonged northward IMF, coinciding with observations of cusp-aligned arcs in the polar region. We observe that the plasma is typically continuous with some substructure observed on length scales of 0.5 - 1.5 R$_E$ which may be linked to the substructure observed in cusp-aligned arcs. The plasma characteristics in each of the three intervals studied are similar. The ion and electron densities are on the order of 0.2 - 1 cm$^{-3}$. The electron energies typically vary between 10$^2$ - 10$^3$ eV. The ion energies are higher compared to the electron energies and range between 10$^2$ - 10$^4$ eV. The ion temperatures are on the order of 5 - 18 MK. The speed of the plasma crossing the Cluster spacecraft is between 4 - 21 km/s which is on the order of magnitude of convection speeds in the magnetotail plasma sheet. We tentatively suggest that this may provide supporting evidence for dual lobe reconnection acting to trap plasma within the magneotsphere and resulting cusp-aligned arc formation.
04 Sep 2024Submitted to ESS Open Archive
09 Sep 2024Published in ESS Open Archive