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Science. 2018 Dec 21;362(6421):1391-1395. doi: 10.1126/science.aat2998. Epub 2018 Nov 15.

Electron-scale dynamics of the diffusion region during symmetric magnetic reconnection in space.

Author information

1
University of New Hampshire, Durham, NH, USA. roy.torbert@unh.edu.
2
Southwest Research Institute (SwRI), San Antonio, TX, USA.
3
University of California, Berkeley, CA, USA.
4
University of Bergen, Bergen, Norway.
5
University of New Hampshire, Durham, NH, USA.
6
NASA Goddard Space Flight Center, Greenbelt, MD, USA.
7
University of Colorado Laboratory for Atmospheric and Space Physics, Boulder, CO, USA.
8
Swedish Institute of Space Physics, Uppsala, Sweden.
9
Space Research Institute, Austrian Academy of Sciences, Graz, Austria.
10
Aerospace Corporation, El Segundo, CA, USA.
11
Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA.
12
University of Maryland, College Park, MD, USA.
13
Blackett Laboratory, Imperial College London, London, UK.
14
University of Texas, San Antonio, TX, USA.
15
University of California, Los Angeles, CA, USA.
16
University of Delaware, Newark, DE, USA.
17
Royal Institute of Technology, Stockholm, Sweden.
18
University of Iowa, Iowa City, IA, USA.
19
Laboratoire de Physique des Plasmas, CNRS/Ecole Polytechnique/Sorbonne Université/Univ. Paris Sud/Observatoire de Paris, Paris, France.
20
Lockheed Martin Advanced Technology Center, Palo Alto, CA, USA.
21
Institut de Recherche en Astrophysique et Planétologie, CNRS, Centre National d'Etudes Spatiales, Université de Toulouse, Toulouse, France.
22
Institute for Space and Astronautical Sciences, Sagamihara, Japan.

Abstract

Magnetic reconnection is an energy conversion process that occurs in many astrophysical contexts including Earth's magnetosphere, where the process can be investigated in situ by spacecraft. On 11 July 2017, the four Magnetospheric Multiscale spacecraft encountered a reconnection site in Earth's magnetotail, where reconnection involves symmetric inflow conditions. The electron-scale plasma measurements revealed (i) super-Alfvénic electron jets reaching 15,000 kilometers per second; (ii) electron meandering motion and acceleration by the electric field, producing multiple crescent-shaped structures in the velocity distributions; and (iii) the spatial dimensions of the electron diffusion region with an aspect ratio of 0.1 to 0.2, consistent with fast reconnection. The well-structured multiple layers of electron populations indicate that the dominant electron dynamics are mostly laminar, despite the presence of turbulence near the reconnection site.

PMID:
30442767
DOI:
10.1126/science.aat2998
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