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

Journal Article · Wed May 09 00:00:00 EDT 2018 · Nature (London)

DOI:https://doi.org/10.1038/s41586-018-0091-5· OSTI ID:1543769

Phan, T. D. ^[1]; Eastwood, J. P. ^[2]; Shay, M. A. ^[3]; Drake, J. F. ^[4]; Sonnerup, B. U. Ö. ^[5]; Fujimoto, M. ^[6]; Cassak, P. A. ^[7]; Øieroset, M. ^[1]; Burch, J. L. ^[8]; Torbert, R. B. ^[9]; Rager, A. C. ^[10]; Dorelli, J. C. ^[11]; Gershman, D. J. ^[11]; Pollock, C. ^[12]; Pyakurel, P. S. ^[3]; Haggerty, C. C. ^[3]; Khotyaintsev, Y. ^[13]; Lavraud, B. ^[14]; Saito, Y. ^[6]; Oka, M. ^[1] ; Ergun, R. E. ^[15]; Retino, A. ^[16]; Le Contel, O. ^[16]; Argall, M. R. ^[9]; Giles, B. L. ^[11]; Moore, T. E. ^[11]; Wilder, F. D. ^[15]; Strangeway, R. J. ^[17]; Russell, C. T. ^[17]; Lindqvist, P. A. ^[18]; Magnes, W. ^[19]

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1. Univ. of California, Berkeley, CA (United States)
2. Imperial College, London (United Kingdom)
3. Univ. of Delaware, Newark, DE (United States)
4. Univ. of Maryland, College Park, MD (United States)
5. Dartmouth College, Hanover, NH (United States)
6. ISAS/JAXA, Sagamihara (Japan)
7. West Virginia Univ., Morgantown, WV (United States)
8. Southwest Research Inst. (SwRI), San Antonio, TX (United States)
9. Univ. of New Hampshire, Durham, NH (United States)
10. The Catholic Univ. of America, Washington, DC (United States); NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
11. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
12. Denali Scientific, Healy, AK (United States)
13. Swedish Inst. of Space Physics, Uppsala (Sweden)
14. Univ. de Toulouse (France)
15. Univ. of Colorado, Boulder, CO (United States)
16. Ecole Polytechnique, Paris(France)
17. Univ. of California, Los Angeles, CA (United States)
18. KTH Royal Inst. of Technology, Stockholm (Sweden)
19. Austrian Academy of Sciences, Graz (Austria)

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. 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. Much of the energy conversion occurs in spatially extended ion exhausts downstream of the diffusion region. 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. 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.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
• Sponsoring Organization: USDOE
• OSTI ID: 1543769
• Journal Information: Nature (London), Vol. 557, Issue 7704; ISSN 0028-0836
• Publisher: Nature Publishing Group
• Country of Publication: United States
• Language: English

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