Electron magnetic reconnection without ion coupling in Earth's turbulent magnetosheath.

Autor: Phan TD; Space Sciences Laboratory, University of California, Berkeley, CA, USA. phan@ssl.berkeley.edu., Eastwood JP; The Blackett Laboratory, Imperial College London, London, UK., Shay MA; University of Delaware, Newark, DE, USA., Drake JF; University of Maryland, College Park, MD, USA., Sonnerup BUÖ; Dartmouth College, Hanover, NH, USA., Fujimoto M; ISAS/JAXA, Sagamihara, Japan., Cassak PA; West Virginia University, Morgantown, WV, USA., Øieroset M; Space Sciences Laboratory, University of California, Berkeley, CA, USA., Burch JL; Southwest Research Institute, San Antonio, TX, USA., Torbert RB; University of New Hampshire, Durham, NH, USA., Rager AC; Catholic University of America, Washington, DC, USA.; NASA Goddard Space Flight Center, Greenbelt, MD, USA., Dorelli JC; NASA Goddard Space Flight Center, Greenbelt, MD, USA., Gershman DJ; NASA Goddard Space Flight Center, Greenbelt, MD, USA., Pollock C; Denali Scientific, Healy, AK, USA., Pyakurel PS; University of Delaware, Newark, DE, USA., Haggerty CC; University of Delaware, Newark, DE, USA., Khotyaintsev Y; Swedish Institute of Space Physics, Uppsala, Sweden., Lavraud B; Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Toulouse, France., Saito Y; ISAS/JAXA, Sagamihara, Japan., Oka M; Space Sciences Laboratory, University of California, Berkeley, CA, USA., Ergun RE; University of Colorado LASP, Boulder, CO, USA., Retino A; CNRS/Ecole Polytechnique, Paris, France., Le Contel O; CNRS/Ecole Polytechnique, Paris, France., Argall MR; University of New Hampshire, Durham, NH, USA., Giles BL; NASA Goddard Space Flight Center, Greenbelt, MD, USA., Moore TE; NASA Goddard Space Flight Center, Greenbelt, MD, USA., Wilder FD; University of Colorado LASP, Boulder, CO, USA., Strangeway RJ; University of California, Los Angeles, Los Angeles, CA, USA., Russell CT; University of California, Los Angeles, Los Angeles, CA, USA., Lindqvist PA; Royal Institute of Technology, Stockholm, Sweden., Magnes W; Space Research Institute, Austrian Academy of Sciences, Graz, Austria.
Jazyk: angličtina
Zdroj: Nature [Nature] 2018 May; Vol. 557 (7704), pp. 202-206. Date of Electronic Publication: 2018 May 09.
DOI: 10.1038/s41586-018-0091-5
Abstrakt: Magnetic reconnection in current sheets is a magnetic-to-particle energy conversion process that is fundamental to many space and laboratory plasma systems. In the standard model of reconnection, this process occurs in a minuscule electron-scale diffusion region 1,2 . On larger scales, ions couple to the newly reconnected magnetic-field lines and are ejected away from the diffusion region in the form of bi-directional ion jets at the ion Alfvén speed 3-5 . Much of the energy conversion occurs in spatially extended ion exhausts downstream of the diffusion region 6 . In turbulent plasmas, which contain a large number of small-scale current sheets, reconnection has long been suggested to have a major role in the dissipation of turbulent energy at kinetic scales 7-11 . However, evidence for reconnection plasma jetting in small-scale turbulent plasmas has so far been lacking. Here we report observations made in Earth's turbulent magnetosheath region (downstream of the bow shock) of an electron-scale current sheet in which diverging bi-directional super-ion-Alfvénic electron jets, parallel electric fields and enhanced magnetic-to-particle energy conversion were detected. Contrary to the standard model of reconnection, the thin reconnecting current sheet was not embedded in a wider ion-scale current layer and no ion jets were detected. Observations of this and other similar, but unidirectional, electron jet events without signatures of ion reconnection reveal a form of reconnection that can drive turbulent energy transfer and dissipation in electron-scale current sheets without ion coupling.
Databáze: MEDLINE
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