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Cozzani G, Khotyaintsev YV, Graham DB, Egedal J, André M, Vaivads A, Alexandrova A, Le Contel O, Nakamura R, Fuselier SA, Russell CT, Burch JL. Structure of a Perturbed Magnetic Reconnection Electron Diffusion Region in the Earth's Magnetotail. PHYSICAL REVIEW LETTERS 2021; 127:215101. [PMID: 34860109 DOI: 10.1103/physrevlett.127.215101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 09/22/2021] [Accepted: 10/07/2021] [Indexed: 06/13/2023]
Abstract
We report in situ observations of an electron diffusion region (EDR) and adjacent separatrix region in the Earth's magnetotail. We observe significant magnetic field oscillations near the lower hybrid frequency which propagate perpendicularly to the reconnection plane. We also find that the strong electron-scale gradients close to the EDR exhibit significant oscillations at a similar frequency. Such oscillations are not expected for a crossing of a steady 2D EDR, and can be explained by a complex motion of the reconnection plane induced by current sheet kinking propagating in the out-of-reconnection-plane direction. Thus, all three spatial dimensions have to be taken into account to explain the observed perturbed EDR crossing. These results shed light on the interplay between magnetic reconnection and current sheet drift instabilities in electron-scale current sheets and highlight the need for adopting a 3D description of the EDR, going beyond the two-dimensional and steady-state conception of reconnection.
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Affiliation(s)
- G Cozzani
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
| | | | - D B Graham
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
| | - J Egedal
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M André
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
| | - A Vaivads
- Space and Plasma Physics, School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, Stockholm 11428, Sweden
| | - A Alexandrova
- Laboratoire de Physique des Plasmas, CNRS, Sorbonne Université, Université Paris-Saclay, Observatoire de Paris, École Polytechnique Institut Polytechnique de Paris, Palaiseau 91128, France
| | - O Le Contel
- Laboratoire de Physique des Plasmas, CNRS, Sorbonne Université, Université Paris-Saclay, Observatoire de Paris, École Polytechnique Institut Polytechnique de Paris, Palaiseau 91128, France
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, Graz 8042, Austria
| | - S A Fuselier
- Southwest Research Institute, San Antonio, Texas 78238, USA
- University of Texas at San Antonio, San Antonio, Texas 78249, USA
| | - C T Russell
- University of California, Los Angeles, California 90095, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, Texas 78238, USA
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Oka M, Fujimoto M, Nakamura TKM, Shinohara I, Nishikawa KI. Magnetic reconnection by a self-retreating X line. PHYSICAL REVIEW LETTERS 2008; 101:205004. [PMID: 19113348 DOI: 10.1103/physrevlett.101.205004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Indexed: 05/27/2023]
Abstract
Particle-in-cell simulations of collisionless magnetic reconnection are performed to study asymmetric reconnection in which an outflow is blocked by a hard wall while leaving sufficiently large room for the outflow of the opposite direction. This condition leads to a slow, roughly constant motion of the diffusion region away from the wall, the so-called "X-line retreat." The typical retreat speed is approximately 0.1 times the Alfvén speed. At the diffusion region, ion flow pattern shows strong asymmetry and the ion stagnation point and the X line are not collocated. A surprise, however, is that the reconnection rate remains the same unaffected by the retreat motion.
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Affiliation(s)
- M Oka
- Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, Alabama 35805, USA.
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Affiliation(s)
- Masahiro Hoshino
- Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan.
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