Electron magnetic reconnection without ion coupling in earth’s turbulent magnetosheath

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Title: Electron magnetic reconnection without ion coupling in earth’s turbulent magnetosheath
Authors: Phan, TD
Eastwood, J
Shay, MA
Drake, JF
Sonnerup, BUO
Fujimoto, M
Cassak, PA
Oieroset, M
Burch, JL
Torbert, RB
Rager, AC
Dorelli, JC
Gershman, DJ
Pollock, C
Pyakurel, PS
Haggerty, CC
Khotyaintsev, Y
Lavraud, B
Saito, Y
Oka, M
Ergun, RE
Retino, A
Le Contel, O
Argall, MR
Giles, B
Moore, TE
Wilder, FD
Strangeway, RJ
Russell, CT
Lindqvist, PA
Magnes, W
Item Type: Journal Article
Abstract: Magnetic reconnection is a magnetic-to-parti cle energy conversion process fundamental to many space and laboratory plasma systems. In the standard model of reconnection, this process occurs in a minuscule electron- scale diffusion region around an X-line 1,2 . On larger scales, the ions couple to the newly-reconnected field lines and are ejected away from the X- line in the form of bi-directional ion jets at the ion Alfvén speed 3-5 . Much of the energy 36 conversion occurs in spatially extended ion exhausts downstream of the diffusion region 6 . In turbulent plasmas, which contain a la rge number of small-scale current sheets, reconnection has long been suggested to play a major role in the dissipation of turbulent energy at kinetic scales 7-11 . However, experimental evidence for reconnection plasma jetting in small-scale turbulent plasmas has so far been lacking. Here we report the discovery in Earth’s turbulent magnetosheath of an elec tron-scale current shee t where diverging bi- directional super-ion-Alfvénic electron jets, pa rallel electric fields, and enhanced magnetic- to-particle energy conversion were observed . Contrary to the standard reconnection picture, the thin reconnecting current sheet was not embedded in a wider ion-scale current layer and no ion jets were detected. Obser vations of this and other similar, but unidirectional, electron jet events without io n reconnection signatures reveal a new form of reconnection that can drive turbulent energy tr ansfer and dissipation in electron-scale current sheets without ion coupling.
Issue Date: 9-May-2018
Date of Acceptance: 30-Jan-2018
ISSN: 0028-0836
Publisher: Nature Publishing Group
Start Page: 202
End Page: 206
Journal / Book Title: Nature
Volume: 557
Copyright Statement: © 2018 Springer Nature Limited. All rights reserved.
Sponsor/Funder: Science and Technology Facilities Council (STFC)
Funder's Grant Number: ST/N000692/1
Keywords: MD Multidisciplinary
General Science & Technology
Publication Status: Published
Appears in Collections:Space and Atmospheric Physics
Faculty of Natural Sciences

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