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Electron Bulk Heating at Saturn's Magnetopause
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  • I Kit Cheng,
  • Nicholas Achilleos,
  • Adam Masters,
  • Gethyn R. Lewis,
  • Mark Kane,
  • Patrick Guio
I Kit Cheng

Corresponding Author:[email protected]

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Nicholas Achilleos
University College London
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Adam Masters
Imperial College London
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Gethyn R. Lewis
Mullard Space Science Laboratory
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Mark Kane
Harford Research Institute
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Patrick Guio
University College London
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Magnetic reconnection at the magnetopause (MP) energises ambient plasma via the< release of magnetic energy and produces an “open” magnetosphere allowing solar wind particles to directly enter the system. At Saturn, the nature of MP reconnection remains unclear. The current study examines electron bulk heating at MP crossings, in order to probe the relationship between observed and predicted reconnection heating proposed by Phan et al. (2013) under open and closed MP, and how this may pertain to the position of the crossings in the Δβ-magnetic shear parameter space. The electron heating for 70 MP crossings made by the Cassini spacecraft from April 2005 to July 2007 was found using 1d and 3d moment methods. Minimum variance analysis was used on the magnetic field data to help indicate whether the MP is open or closed. We found better agreement between observed and predicted heating for events suggestive of locally ‘open’ MP. For events suggestive of locally ‘closed’ MP, we observed a cluster of points consistent with no electron heating, but also numerous cases with significant heating. Examining the events in the Δβ-magnetic shear parameter space, we find 83% of events without evidence of energisation were situated in the ‘reconnection suppressed’ regime, whilst between 43% to 68% of events with energisation lie in the ‘reconnection possible’ regime depending on the threshold used. The discrepancies could be explained by a combination of spatial and temporal variability which makes it possible to observe heated electrons with different conditions from the putative reconnection site.
May 2021Published in Journal of Geophysical Research: Space Physics volume 126 issue 5. 10.1029/2020JA028800