1
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Hasegawa H, Argall MR, Aunai N, Bandyopadhyay R, Bessho N, Cohen IJ, Denton RE, Dorelli JC, Egedal J, Fuselier SA, Garnier P, Génot V, Graham DB, Hwang KJ, Khotyaintsev YV, Korovinskiy DB, Lavraud B, Lenouvel Q, Li TC, Liu YH, Michotte de Welle B, Nakamura TKM, Payne DS, Petrinec SM, Qi Y, Rager AC, Reiff PH, Schroeder JM, Shuster JR, Sitnov MI, Stephens GK, Swisdak M, Tian AM, Torbert RB, Trattner KJ, Zenitani S. Advanced Methods for Analyzing in-Situ Observations of Magnetic Reconnection. SPACE SCIENCE REVIEWS 2024; 220:68. [PMID: 39234211 PMCID: PMC11369046 DOI: 10.1007/s11214-024-01095-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 07/19/2024] [Indexed: 09/06/2024]
Abstract
There is ample evidence for magnetic reconnection in the solar system, but it is a nontrivial task to visualize, to determine the proper approaches and frames to study, and in turn to elucidate the physical processes at work in reconnection regions from in-situ measurements of plasma particles and electromagnetic fields. Here an overview is given of a variety of single- and multi-spacecraft data analysis techniques that are key to revealing the context of in-situ observations of magnetic reconnection in space and for detecting and analyzing the diffusion regions where ions and/or electrons are demagnetized. We focus on recent advances in the era of the Magnetospheric Multiscale mission, which has made electron-scale, multi-point measurements of magnetic reconnection in and around Earth's magnetosphere.
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Affiliation(s)
- H. Hasegawa
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252-5210 Japan
| | - M. R. Argall
- Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824 USA
| | - N. Aunai
- CNRS, Ecole polytechnique, Sorbonne Université, Université Paris Sud, Observatoire de Paris, Institut Polytechnique de Paris, Université Paris-Saclay, PSL Research Univsersity, Laboratoire de Physique des Plasmas, Palaiseau, France
| | - R. Bandyopadhyay
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 USA
| | - N. Bessho
- Department of Astronomy, University of Maryland, College Park, MD 20742 USA
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA
| | - I. J. Cohen
- Applied Physics Laboratory, The Johns Hopkins University, Laurel, MD USA
| | - R. E. Denton
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH USA
| | - J. C. Dorelli
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA
| | - J. Egedal
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706 USA
| | - S. A. Fuselier
- Southwest Research Institute, San Antonio, TX USA
- University of Texas at San Antonio, San Antonio, TX USA
| | - P. Garnier
- Institut de Recherche en Astrophysique et Planétologie, CNRS, Université Paul Sabatier, CNES, Toulouse, France
| | - V. Génot
- Institut de Recherche en Astrophysique et Planétologie, CNRS, Université Paul Sabatier, CNES, Toulouse, France
| | - D. B. Graham
- Swedish Institute of Space Physics, Uppsala, Sweden
| | - K. J. Hwang
- Southwest Research Institute, San Antonio, TX USA
| | - Y. V. Khotyaintsev
- Swedish Institute of Space Physics, Uppsala, Sweden
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - D. B. Korovinskiy
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - B. Lavraud
- Institut de Recherche en Astrophysique et Planétologie, CNRS, Université Paul Sabatier, CNES, Toulouse, France
- Laboratoire d’Astrophysique de Bordeaux, Université Bordeaux, CNRS, Pessac, France
| | - Q. Lenouvel
- Institut de Recherche en Astrophysique et Planétologie, CNRS, Université Paul Sabatier, CNES, Toulouse, France
| | - T. C. Li
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH USA
| | - Y.-H. Liu
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH USA
| | - B. Michotte de Welle
- CNRS, Ecole polytechnique, Sorbonne Université, Université Paris Sud, Observatoire de Paris, Institut Polytechnique de Paris, Université Paris-Saclay, PSL Research Univsersity, Laboratoire de Physique des Plasmas, Palaiseau, France
| | - T. K. M. Nakamura
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
- Krimgen LLC, Hiroshima, 732-0828 Japan
| | - D. S. Payne
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD USA
| | | | - Y. Qi
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO USA
| | - A. C. Rager
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 USA
| | - P. H. Reiff
- Rice Space Institute, Rice University, Houston, TX USA
| | - J. M. Schroeder
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706 USA
| | - J. R. Shuster
- Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824 USA
| | - M. I. Sitnov
- Applied Physics Laboratory, The Johns Hopkins University, Laurel, MD USA
| | - G. K. Stephens
- Applied Physics Laboratory, The Johns Hopkins University, Laurel, MD USA
| | - M. Swisdak
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD USA
| | - A. M. Tian
- Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Institute of Space Sciences, Shandong University, Weihai, Shandong 264209 People’s Republic of China
| | - R. B. Torbert
- Southwest Research Institute, Durham, NH USA
- Physics Department, University of New Hampshire, Durham, NH USA
| | - K. J. Trattner
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO USA
| | - S. Zenitani
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
- Research Center for Urban Safety and Security, Kobe University, Kobe, 657-8501 Japan
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2
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Yoo J, Ng J, Ji H, Bose S, Goodman A, Alt A, Chen LJ, Shi P, Yamada M. Anomalous Resistivity and Electron Heating by Lower Hybrid Drift Waves during Magnetic Reconnection with a Guide Field. PHYSICAL REVIEW LETTERS 2024; 132:145101. [PMID: 38640378 DOI: 10.1103/physrevlett.132.145101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 12/29/2023] [Accepted: 02/07/2024] [Indexed: 04/21/2024]
Abstract
The lower hybrid drift wave (LHDW) has been a candidate for anomalous resistivity and electron heating inside the electron diffusion region of magnetic reconnection. In a laboratory reconnection layer with a finite guide field, quasielectrostatic LHDW (ES-LHDW) propagating along the direction nearly perpendicular to the local magnetic field is excited in the electron diffusion region. ES-LHDW generates large density fluctuations (δn_{e}, about 25% of the mean density) that are correlated with fluctuations in the out-of-plane electric field (δE_{Y}, about twice larger than the mean reconnection electric field). With a small phase difference (∼30°) between two fluctuating quantities, the anomalous resistivity associated with the observed ES-LHDW is twice larger than the classical resistivity and accounts for 20% of the mean reconnection electric field. After we verify the linear relationship between δn_{e} and δE_{Y}, anomalous electron heating by LHDW is estimated by a quasilinear analysis. The estimated electron heating is about 2.6±0.3 MW/m^{3}, which exceeds the classical Ohmic heating of about 2.0±0.2 MW/m^{3}. This LHDW-driven heating is consistent with the observed trend of higher electron temperatures when the wave amplitude is larger. Presented results provide the first direct estimate of anomalous resistivity and electron heating power by LHDW, which demonstrates the importance of wave-particle interactions in magnetic reconnection.
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Affiliation(s)
- Jongsoo Yoo
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08542, USA
| | - Jonathan Ng
- Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA
| | - Hantao Ji
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08542, USA
- Department of Astrophysical Sciences, Princeton University, New Jersey 08544, USA
| | - Sayak Bose
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08542, USA
| | - Aaron Goodman
- Department of Mechanical and Aerospace Engineering, Princeton University, New Jersey 08544, USA
| | - Andrew Alt
- Department of Astrophysical Sciences, Princeton University, New Jersey 08544, USA
| | - Li-Jen Chen
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - Peiyun Shi
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08542, USA
| | - Masaaki Yamada
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08542, USA
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3
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Zhang Q, Guo F, Daughton W, Li H, Le A, Phan T, Desai M. Multispecies Ion Acceleration in 3D Magnetic Reconnection with Hybrid-Kinetic Simulations. PHYSICAL REVIEW LETTERS 2024; 132:115201. [PMID: 38563953 DOI: 10.1103/physrevlett.132.115201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 01/29/2024] [Indexed: 04/04/2024]
Abstract
Magnetic reconnection drives multispecies particle acceleration broadly in space and astrophysics. We perform the first 3D hybrid simulations (fluid electrons, kinetic ions) that contain sufficient scale separation to produce nonthermal heavy-ion acceleration, with fragmented flux ropes critical for accelerating all species. We demonstrate the acceleration of all ion species (up to Fe) into power-law spectra with similar indices, by a common Fermi acceleration mechanism. The upstream ion velocities influence the first Fermi reflection for injection. The subsequent onsets of Fermi acceleration are delayed for ions with lower charge-mass ratios (Q/M), until growing flux ropes magnetize them. This leads to a species-dependent maximum energy/nucleon ∝(Q/M)^{α}. These findings are consistent with in situ observations in reconnection regions, suggesting Fermi acceleration as the dominant multispecies ion acceleration mechanism.
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Affiliation(s)
- Qile Zhang
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Fan Guo
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - William Daughton
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Hui Li
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Ari Le
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Tai Phan
- Space Sciences Laboratory, University of California, Berkeley, Berkeley, California 94720, USA
| | - Mihir Desai
- Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238, USA and Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249, USA
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4
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Ji H, Yoo J, Fox W, Yamada M, Argall M, Egedal J, Liu YH, Wilder R, Eriksson S, Daughton W, Bergstedt K, Bose S, Burch J, Torbert R, Ng J, Chen LJ. Laboratory Study of Collisionless Magnetic Reconnection. SPACE SCIENCE REVIEWS 2023; 219:76. [PMID: 38023292 PMCID: PMC10651714 DOI: 10.1007/s11214-023-01024-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 11/03/2023] [Indexed: 12/01/2023]
Abstract
A concise review is given on the past two decades' results from laboratory experiments on collisionless magnetic reconnection in direct relation with space measurements, especially by the Magnetospheric Multiscale (MMS) mission. Highlights include spatial structures of electromagnetic fields in ion and electron diffusion regions as a function of upstream symmetry and guide field strength, energy conversion and partitioning from magnetic field to ions and electrons including particle acceleration, electrostatic and electromagnetic kinetic plasma waves with various wavelengths, and plasmoid-mediated multiscale reconnection. Combined with the progress in theoretical, numerical, and observational studies, the physics foundation of fast reconnection in collisionless plasmas has been largely established, at least within the parameter ranges and spatial scales that were studied. Immediate and long-term future opportunities based on multiscale experiments and space missions supported by exascale computation are discussed, including dissipation by kinetic plasma waves, particle heating and acceleration, and multiscale physics across fluid and kinetic scales.
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Affiliation(s)
- H. Ji
- Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, 08544 New Jersey USA
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, 08543 New Jersey USA
| | - J. Yoo
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, 08543 New Jersey USA
| | - W. Fox
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, 08543 New Jersey USA
| | - M. Yamada
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, 08543 New Jersey USA
| | - M. Argall
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, 8 College Road, Durham, 03824 New Hampshire USA
| | - J. Egedal
- Department of Physics, University of Wisconsin - Madison, 1150 University Avenue, Madison, 53706 Wisconsin USA
| | - Y.-H. Liu
- Department of Physics and Astronomy, Dartmouth College, 17 Fayerweather Hill Road, Hanover, 03755 New Hampshire USA
| | - R. Wilder
- Department of Physics, University of Texas at Arlington, 701 S. Nedderman Drive, Arlington, 76019 Texas USA
| | - S. Eriksson
- Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, 1234 Innovation Drive, Boulder, 80303 Colorado USA
| | - W. Daughton
- Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, 87545 New Mexico USA
| | - K. Bergstedt
- Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, 08544 New Jersey USA
| | - S. Bose
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, 08543 New Jersey USA
| | - J. Burch
- Southwest Research Institute, 6220 Culebra Road, San Antonio, 78238 Texas USA
| | - R. Torbert
- Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, 8 College Road, Durham, 03824 New Hampshire USA
| | - J. Ng
- Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, 08543 New Jersey USA
- Department of Astronomy, University of Maryland, 4296 Stadium Drive, College Park, 20742 Maryland USA
- Goddard Space Flight Center, Mail Code 130, Greenbelt, 20771 Maryland USA
| | - L.-J. Chen
- Goddard Space Flight Center, Mail Code 130, Greenbelt, 20771 Maryland USA
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5
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Oka M, Birn J, Egedal J, Guo F, Ergun RE, Turner DL, Khotyaintsev Y, Hwang KJ, Cohen IJ, Drake JF. Particle Acceleration by Magnetic Reconnection in Geospace. SPACE SCIENCE REVIEWS 2023; 219:75. [PMID: 37969745 PMCID: PMC10630319 DOI: 10.1007/s11214-023-01011-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 10/05/2023] [Indexed: 11/17/2023]
Abstract
Particles are accelerated to very high, non-thermal energies during explosive energy-release phenomena in space, solar, and astrophysical plasma environments. While it has been established that magnetic reconnection plays an important role in the dynamics of Earth's magnetosphere, it remains unclear how magnetic reconnection can further explain particle acceleration to non-thermal energies. Here we review recent progress in our understanding of particle acceleration by magnetic reconnection in Earth's magnetosphere. With improved resolutions, recent spacecraft missions have enabled detailed studies of particle acceleration at various structures such as the diffusion region, separatrix, jets, magnetic islands (flux ropes), and dipolarization front. With the guiding-center approximation of particle motion, many studies have discussed the relative importance of the parallel electric field as well as the Fermi and betatron effects. However, in order to fully understand the particle acceleration mechanism and further compare with particle acceleration in solar and astrophysical plasma environments, there is a need for further investigation of, for example, energy partition and the precise role of turbulence.
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Affiliation(s)
- Mitsuo Oka
- Space Sciences Laboratory, University of California Berkeley, 7 Gauss Way, Berkeley, 94720 CA USA
| | - Joachim Birn
- Center for Space Plasma Physics, Space Science Institute, 4765 Walnut Street, Boulder, 80301 CO USA
- Los Alamos National Laboratory, Los Alamos, 87545 NM USA
| | - Jan Egedal
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, 53706 WI USA
| | - Fan Guo
- Los Alamos National Laboratory, Los Alamos, 87545 NM USA
| | - Robert E. Ergun
- Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, 80303 CO USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, 2000 Colorado Avenue, Boulder, 80309 CO USA
| | - Drew L. Turner
- The Johns Hopkins Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, 20723 MD USA
| | | | - Kyoung-Joo Hwang
- Southwest Research Institute, 6220 Culebra Road, San Antonio, 78238 TX USA
| | - Ian J. Cohen
- The Johns Hopkins Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, 20723 MD USA
| | - James F. Drake
- Department of Physics, The Institute for Physical Science and Technology and The Joint Space Science Institute, University of Maryland, College Park, 20742 MD USA
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6
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Motoba T, Sitnov MI, Stephens GK, Gershman DJ. A New Perspective on Magnetotail Electron and Ion Divergent Flows: MMS Observations. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2022; 127:e2022JA030514. [PMID: 36591322 PMCID: PMC9788156 DOI: 10.1029/2022ja030514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 08/17/2022] [Accepted: 09/13/2022] [Indexed: 06/17/2023]
Abstract
Fast divergent flows of electrons and ions in the magnetotail plasma sheet are conventionally interpreted as a key reconnection signature caused by the magnetic topology change at the X-line. Therefore, reversals of the x-component (V x⊥) of the plasma flow perpendicular to the magnetic field must correlate with the sign changes in the north-south component of the magnetic field (B z ). Here we present observations of the flow reversals that take place with no correlated B z reversals. We report six such events, which were measured with the high-resolution plasma and fields instruments of the Magnetospheric Multiscale mission. We found that electron flow reversals in the absence of B z reversals (a) have amplitudes of ∼1,000-2,000 km s-1 and durations of a few seconds; (b) are embedded into larger-scale ion flow reversals with enhanced ion agyrotropy; and (c) compared with conventional reconnection outflows around the electron diffusion regions (EDRs), have less (if ever) pronounced electron agyrotropy, dawnward electron flow amplitude, and electric field strength toward the neutral sheet, although their energy conversion parameters, including the Joule heating rate, are quite substantial. These results suggest that such flow reversals develop in the ion-demagnetization regions away from electron-scale current sheets, in particular the EDRs, and yet they play an important role in the energy conversion. These divergent flows are interpreted as precursors of the flow-driven reconnection onsets provided by the ion tearing or the ballooning/interchange instability.
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Affiliation(s)
- T. Motoba
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - M. I. Sitnov
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
| | - G. K. Stephens
- The Johns Hopkins University Applied Physics LaboratoryLaurelMDUSA
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7
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Alho M, Battarbee M, Pfau‐Kempf Y, Khotyaintsev YV, Nakamura R, Cozzani G, Ganse U, Turc L, Johlander A, Horaites K, Tarvus V, Zhou H, Grandin M, Dubart M, Papadakis K, Suni J, George H, Bussov M, Palmroth M. Electron Signatures of Reconnection in a Global eVlasiator Simulation. GEOPHYSICAL RESEARCH LETTERS 2022; 49:e2022GL098329. [PMID: 36249284 PMCID: PMC9541212 DOI: 10.1029/2022gl098329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/13/2022] [Accepted: 06/02/2022] [Indexed: 06/16/2023]
Abstract
Geospace plasma simulations have progressed toward more realistic descriptions of the solar wind-magnetosphere interaction from magnetohydrodynamic to hybrid ion-kinetic, such as the state-of-the-art Vlasiator model. Despite computational advances, electron scales have been out of reach in a global setting. eVlasiator, a novel Vlasiator submodule, shows for the first time how electromagnetic fields driven by global hybrid-ion kinetics influence electrons, resulting in kinetic signatures. We analyze simulated electron distributions associated with reconnection sites and compare them with Magnetospheric Multiscale (MMS) spacecraft observations. Comparison with MMS shows that key electron features, such as reconnection inflows, heated outflows, flat-top distributions, and bidirectional streaming, are in remarkable agreement. Thus, we show that many reconnection-related features can be reproduced despite strongly truncated electron physics and an ion-scale spatial resolution. Ion-scale dynamics and ion-driven magnetic fields are shown to be significantly responsible for the environment that produces electron dynamics observed by spacecraft in near-Earth plasmas.
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Affiliation(s)
- M. Alho
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - M. Battarbee
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - Y. Pfau‐Kempf
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | | | - R. Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - G. Cozzani
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - U. Ganse
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - L. Turc
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - A. Johlander
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
- Swedish Institute of Space PhysicsUppsalaSweden
| | - K. Horaites
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - V. Tarvus
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - H. Zhou
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - M. Grandin
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - M. Dubart
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - K. Papadakis
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - J. Suni
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - H. George
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - M. Bussov
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - M. Palmroth
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
- Finnish Meteorological InstituteHelsinkiFinland
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8
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Hasegawa H, Denton RE, Nakamura TKM, Genestreti KJ, Phan TD, Nakamura R, Hwang K, Ahmadi N, Shi QQ, Hesse M, Burch JL, Webster JM, Torbert RB, Giles BL, Gershman DJ, Russell CT, Strangeway RJ, Wei HY, Lindqvist P, Khotyaintsev YV, Ergun RE, Saito Y. Magnetic Field Annihilation in a Magnetotail Electron Diffusion Region With Electron-Scale Magnetic Island. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2022; 127:e2022JA030408. [PMID: 36248013 PMCID: PMC9541864 DOI: 10.1029/2022ja030408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 05/27/2022] [Accepted: 06/20/2022] [Indexed: 06/16/2023]
Abstract
We present observations in Earth's magnetotail by the Magnetospheric Multiscale spacecraft that are consistent with magnetic field annihilation, rather than magnetic topology change, causing fast magnetic-to-electron energy conversion in an electron-scale current sheet. Multi-spacecraft analysis for the magnetic field reconstruction shows that an electron-scale magnetic island was embedded in the observed electron diffusion region (EDR), suggesting an elongated shape of the EDR. Evidence for the annihilation was revealed in the form of the island growing at a rate much lower than expected for the standard X-type geometry of the EDR, which indicates that magnetic flux injected into the EDR was not ejected from the X-point or accumulated in the island, but was dissipated in the EDR. This energy conversion process is in contrast to that in the standard EDR of a reconnecting current sheet where the energy of antiparallel magnetic fields is mostly converted to electron bulk-flow energy. Fully kinetic simulation also demonstrates that an elongated EDR is subject to the formation of electron-scale magnetic islands in which fast but transient annihilation can occur. Consistent with the observations and simulation, theoretical analysis shows that fast magnetic diffusion can occur in an elongated EDR in the presence of nongyrotropic electron effects. We suggest that the annihilation in elongated EDRs may contribute to the dissipation of magnetic energy in a turbulent collisionless plasma.
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Affiliation(s)
- H. Hasegawa
- Institute of Space and Astronautical ScienceJapan Aerospace Exploration AgencySagamiharaJapan
| | - R. E. Denton
- Department of Physics and AstronomyDartmouth CollegeHanoverNHUSA
| | - T. K. M. Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
- Institute of PhysicsUniversity of GrazGrazAustria
| | | | - T. D. Phan
- Space Sciences LaboratoryUniversity of CaliforniaBerkeleyCAUSA
| | - R. Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - K.‐J. Hwang
- Southwest Research InstituteSan AntonioTXUSA
| | - N. Ahmadi
- Laboratory for Atmospheric and Space PhysicsUniversity of ColoradoBoulderCOUSA
| | - Q. Q. Shi
- Shandong Provincial Key Laboratory of Optical Astronomy and Solar‐Terrestrial EnvironmentInstitute of Space SciencesShandong UniversityWeihaiChina
| | - M. Hesse
- NASA Ames Research CenterMoffett FieldCAUSA
| | - J. L. Burch
- Southwest Research InstituteSan AntonioTXUSA
| | | | - R. B. Torbert
- Institute of PhysicsUniversity of GrazGrazAustria
- Physics DepartmentUniversity of New HampshireDurhamNHUSA
| | - B. L. Giles
- NASA Goddard Space Flight CenterGreenbeltMDUSA
| | | | - C. T. Russell
- Department of Earth, Planetary, and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - R. J. Strangeway
- Department of Earth, Planetary, and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - H. Y. Wei
- Department of Earth, Planetary, and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | | | | | - R. E. Ergun
- Department of Astrophysical and Planetary SciencesUniversity of ColoradoBoulderCOUSA
| | - Y. Saito
- Institute of Space and Astronautical ScienceJapan Aerospace Exploration AgencySagamiharaJapan
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9
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Li X, Wang R, Lu Q, Russell CT, Lu S, Cohen IJ, Ergun RE, Wang S. Three-dimensional network of filamentary currents and super-thermal electrons during magnetotail magnetic reconnection. Nat Commun 2022; 13:3241. [PMID: 35688827 PMCID: PMC9187682 DOI: 10.1038/s41467-022-31025-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 05/24/2022] [Indexed: 11/24/2022] Open
Abstract
Magnetic reconnection is a fundamental plasma process by which magnetic field lines on two sides of the current sheet flow inward to yield an X-line topology. It is responsible for producing energetic electrons in explosive phenomena in space, astrophysical, and laboratorial plasmas. The X-line region is supposed to be the important place for generating energetic electrons. However, how these energetic electrons are generated in such a limited region is still poorly understood. Here, using Magnetospheric multiscale mission data acquired in Earth’s magnetotail, we present direct evidence of super-thermal electrons up to 300 keV inside an X-line region, and the electrons display a power-law spectrum with an index of about 8.0. Concurrently, three-dimensional network of dynamic filamentary currents in electron scale is observed and leads to electromagnetic turbulence therein. The observations indicate that the electrons are effectively accelerated while the X-line region evolves into turbulence with a complex filamentary current network. Magnetotail reconnection plays an important role in explosive energy conversion. Here, the authors show direct evidence of super-thermal electrons up to 300 keV within X-line region in Earth’s magnetotail, indicating effective electron acceleration due to turbulence.
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Affiliation(s)
- Xinmin Li
- CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei, 230026, China.,CAS Center for Excellence in Comparative Planetology, Hefei, China.,Anhui Mengcheng Geophysics National Observation and Research Station, University of Science and Technology of China, Mengcheng, 233500, Anhui, China
| | - Rongsheng Wang
- CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei, 230026, China. .,CAS Center for Excellence in Comparative Planetology, Hefei, China. .,Anhui Mengcheng Geophysics National Observation and Research Station, University of Science and Technology of China, Mengcheng, 233500, Anhui, China.
| | - Quanming Lu
- CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei, 230026, China. .,CAS Center for Excellence in Comparative Planetology, Hefei, China. .,Anhui Mengcheng Geophysics National Observation and Research Station, University of Science and Technology of China, Mengcheng, 233500, Anhui, China.
| | - Christopher T Russell
- Earth Planetary and Space Sciences, University of California, Los Angeles, CA, 90095, USA
| | - San Lu
- CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei, 230026, China.,CAS Center for Excellence in Comparative Planetology, Hefei, China.,Anhui Mengcheng Geophysics National Observation and Research Station, University of Science and Technology of China, Mengcheng, 233500, Anhui, China
| | - Ian J Cohen
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - R E Ergun
- Department for Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO, USA
| | - Shui Wang
- CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei, 230026, China.,CAS Center for Excellence in Comparative Planetology, Hefei, China.,Anhui Mengcheng Geophysics National Observation and Research Station, University of Science and Technology of China, Mengcheng, 233500, Anhui, China
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10
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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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11
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Hasegawa H, Nakamura TKM, Denton RE. Reconstruction of the Electron Diffusion Region With Inertia and Compressibility Effects. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2021; 126:e2021JA029841. [PMID: 35864949 PMCID: PMC9286637 DOI: 10.1029/2021ja029841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 10/11/2021] [Accepted: 10/13/2021] [Indexed: 06/15/2023]
Abstract
A method based on electron magnetohydrodynamics (EMHD) for the reconstruction of steady, two-dimensional plasma and magnetic field structures from data taken by a single spacecraft, first developed by Sonnerup et al. (2016), https://doi.org/10.1002/2016ja022430, is extended to accommodate inhomogeneity of the electron density and temperature, electron inertia effects, and guide magnetic field in and around the electron diffusion region (EDR), the central part of the magnetic reconnection region. The new method assumes that the electron density and temperature are constant along, but may vary across, the magnetic field lines. We present two models for the reconstruction of electron streamlines, one of which is not constrained by any specific formula for the electron pressure tensor term in the generalized Ohm's law that is responsible for electron unmagnetization in the EDR, and the other is a modification of the original model to include the inertia and compressibility effects. Benchmark tests using data from fully kinetic simulations show that our new method is applicable to both antiparallel and guide-field (component) reconnection, and the electron velocity field can be better reconstructed by including the inertia effects. The new EMHD reconstruction technique has been applied to an EDR of magnetotail reconnection encountered by the Magnetospheric Multiscale spacecraft on 11 July 2017, reported by Torbert et al. (2018), https://doi.org/10.1126/science.aat2998 and reconstructed with the original inertia-less version by Hasegawa et al. (2019), https://doi.org/10.1029/2018ja026051, which demonstrates that the new method better performs in recovering the electric field and electron streamlines than the original version.
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Affiliation(s)
- H. Hasegawa
- Institute of Space and Astronautical ScienceJapan Aerospace Exploration AgencySagamiharaJapan
| | | | - R. E. Denton
- Department of Physics and AstronomyDartmouth CollegeHanoverNHUSA
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12
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Verscharen D, Wicks RT, Alexandrova O, Bruno R, Burgess D, Chen CHK, D’Amicis R, De Keyser J, de Wit TD, Franci L, He J, Henri P, Kasahara S, Khotyaintsev Y, Klein KG, Lavraud B, Maruca BA, Maksimovic M, Plaschke F, Poedts S, Reynolds CS, Roberts O, Sahraoui F, Saito S, Salem CS, Saur J, Servidio S, Stawarz JE, Štverák Š, Told D. A Case for Electron-Astrophysics. EXPERIMENTAL ASTRONOMY 2021; 54:473-519. [PMID: 36915623 PMCID: PMC9998602 DOI: 10.1007/s10686-021-09761-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 05/07/2021] [Indexed: 06/18/2023]
Abstract
The smallest characteristic scales, at which electron dynamics determines the plasma behaviour, are the next frontier in space and astrophysical plasma research. The analysis of astrophysical processes at these scales lies at the heart of the research theme of electron-astrophysics. Electron scales are the ultimate bottleneck for dissipation of plasma turbulence, which is a fundamental process not understood in the electron-kinetic regime. In addition, plasma electrons often play an important role for the spatial transfer of thermal energy due to the high heat flux associated with their velocity distribution. The regulation of this electron heat flux is likewise not understood. By focussing on these and other fundamental electron processes, the research theme of electron-astrophysics links outstanding science questions of great importance to the fields of space physics, astrophysics, and laboratory plasma physics. In this White Paper, submitted to ESA in response to the Voyage 2050 call, we review a selection of these outstanding questions, discuss their importance, and present a roadmap for answering them through novel space-mission concepts.
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Affiliation(s)
- Daniel Verscharen
- Mullard Space Science Laboratory, University College London, Dorking, UK
- Space Science Center, University of New Hampshire, Durham, NH USA
| | - Robert T. Wicks
- Mullard Space Science Laboratory, University College London, Dorking, UK
- Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle-upon-Tyne, UK
| | - Olga Alexandrova
- Laboratoire d’Études Spatiales et d’Instrumentation en Astrophysique, Observatoire de Paris-Meudon, Paris, France
| | - Roberto Bruno
- Instituto di Astrofisica e Planetologia Spaziali, INAF, Rome, Italy
| | - David Burgess
- School of Physics and Astronomy, Queen Mary University of London, London, UK
| | | | | | - Johan De Keyser
- Royal Belgian Institute for Space Aeronomy, Brussels, Belgium
| | - Thierry Dudok de Wit
- Laboratoire de Physique et Chimie de l’Environment et de l’Espace, CNRS, University of Orléans and CNES, Orléans, France
| | - Luca Franci
- School of Physics and Astronomy, Queen Mary University of London, London, UK
- Osservatorio Astrofisico di Arcetri, INAF, Firenze, Italy
| | - Jiansen He
- School of Earth and Space Sciences, Peking University, Beijing, China
| | - Pierre Henri
- Laboratoire de Physique et Chimie de l’Environment et de l’Espace, CNRS, University of Orléans and CNES, Orléans, France
- CNRS, UCA, OCA, Lagrange, Nice, France
| | - Satoshi Kasahara
- Department of Earth and Planetary Science, University of Tokyo, Tokyo, Japan
| | | | - Kristopher G. Klein
- Lunar and Planetary Laboratory and Department of Planetary Sciences, University of Arizona, Tucson, AZ USA
| | - Benoit Lavraud
- Laboratoire d’astrophysique de Bordeaux, Université de Bordeaux, CNRS, Pessac, France
- Institut de Recherche en Astrophysique et Planétologie, CNRS, UPS, CNES, Université de Toulouse, Toulouse, France
| | - Bennett A. Maruca
- Department of Physics and Astronomy, Bartol Research Institute, University of Delaware, Newark, DE USA
| | - Milan Maksimovic
- Laboratoire d’Études Spatiales et d’Instrumentation en Astrophysique, Observatoire de Paris-Meudon, Paris, France
| | | | - Stefaan Poedts
- Centre for Mathematical Plasma Astrophysics, KU Leuven, Leuven, Belgium
- Institute of Physics, University of Maria Curie-Skłodowska, Lublin, Poland
| | | | - Owen Roberts
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - Fouad Sahraoui
- Laboratoire de Physique des Plasmas, CNRS, École Polytechnique, Sorbonne Université, Observatoire de Paris-Meudon, Paris Saclay, Palaiseau, France
| | - Shinji Saito
- Space Environment Laboratory, National Institute of Information and Communications Technology, Tokyo, Japan
| | - Chadi S. Salem
- Space Sciences Laboratory, University of California, Berkeley, CA USA
| | - Joachim Saur
- Institut für Geophysik und Meteorologie, University of Cologne, Cologne, Germany
| | - Sergio Servidio
- Department of Physics, Università della Calabria, Rende, Italy
| | | | - Štěpán Štverák
- Astronomical Institute and Institute of Atmospheric Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - Daniel Told
- Max Planck Institute for Plasma Physics, Garching, Germany
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13
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Shi P, Srivastav P, Beatty C, Nirwan RS, Scime EE. Incoherent Thomson scattering system for PHAse space MApping (PHASMA) experiment. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:033102. [PMID: 33820086 DOI: 10.1063/5.0040606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/18/2021] [Indexed: 06/12/2023]
Abstract
A new incoherent Thomson scattering system measures the evolution of electron velocity distribution functions perpendicular and parallel to the ambient magnetic field during kinking of a single flux rope and merging of two flux ropes through magnetic reconnection. The Thomson scattering system provides sub-millimeter spatial resolution, sufficient to diagnose the several millimeters sized magnetic reconnection electron diffusion region in the PHAse Space MAppgin experiment. Due to the relatively modest plasma density ∼1019 m-3 and electron temperature ∼1 eV, stray light suppression is critical for these measurements. Two volume Bragg gratings are used in series as a notch filter with a spectral bandwidth <0.1 nm in the collection branch. A CCD with a Gen III intensifier with peak quantum efficiency >47% is used as the detector in a 1.3 m spectrometer. Preliminary results of gun plasma electron temperature will be reported and compared with measurements obtained from a triple Langmuir probe.
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Affiliation(s)
- Peiyun Shi
- Department of Physics and Astronomy, West Virginia University and Center for KINETIC Plasma Physics, Morgantown, West Virginia 26506, USA
| | - Prabhakar Srivastav
- Department of Physics and Astronomy, West Virginia University and Center for KINETIC Plasma Physics, Morgantown, West Virginia 26506, USA
| | - Cuyler Beatty
- Department of Physics and Astronomy, West Virginia University and Center for KINETIC Plasma Physics, Morgantown, West Virginia 26506, USA
| | - Ripudaman Singh Nirwan
- Department of Physics and Astronomy, West Virginia University and Center for KINETIC Plasma Physics, Morgantown, West Virginia 26506, USA
| | - Earl E Scime
- Department of Physics and Astronomy, West Virginia University and Center for KINETIC Plasma Physics, Morgantown, West Virginia 26506, USA
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14
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Eastwood JP, Goldman MV, Phan TD, Stawarz JE, Cassak PA, Drake JF, Newman D, Lavraud B, Shay MA, Ergun RE, Burch JL, Gershman DJ, Giles BL, Lindqvist PA, Torbert RB, Strangeway RJ, Russell CT. Energy Flux Densities near the Electron Dissipation Region in Asymmetric Magnetopause Reconnection. PHYSICAL REVIEW LETTERS 2020; 125:265102. [PMID: 33449730 DOI: 10.1103/physrevlett.125.265102] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 10/29/2020] [Accepted: 11/24/2020] [Indexed: 06/12/2023]
Abstract
Magnetic reconnection is of fundamental importance to plasmas because of its role in releasing and repartitioning stored magnetic energy. Previous results suggest that this energy is predominantly released as ion enthalpy flux along the reconnection outflow. Using Magnetospheric Multiscale data we find the existence of very significant electron energy flux densities in the vicinity of the magnetopause electron dissipation region, orthogonal to the ion energy outflow. These may significantly impact models of electron transport, wave generation, and particle acceleration.
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Affiliation(s)
- J P Eastwood
- The Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - M V Goldman
- Department of Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - T D Phan
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
| | - J E Stawarz
- The Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - P A Cassak
- Department of Physics and Astronomy and Center for KINETIC Plasma Physics, West Virginia University, Morgantown, West Virginia 26506, USA
| | - J F Drake
- Department of Physics/Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
| | - D Newman
- Department of Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - B Lavraud
- Laboratoire d'Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
- Institut de Recherche en Astrophysique et Planétologie, CNRS, CNES, Université de Toulouse, 31028 Toulouse Cedex 4, France
| | - M A Shay
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
| | - R E Ergun
- LASP/Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, Texas 78238, USA
| | - D J Gershman
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - B L Giles
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - P A Lindqvist
- KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - R B Torbert
- Southwest Research Institute, San Antonio, Texas 78238, USA
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - R J Strangeway
- Institute of Geophysics, Earth, Planetary, and Space Sciences, University of California, Los Angeles, Los Angeles, California 90095, USA
| | - C T Russell
- Institute of Geophysics, Earth, Planetary, and Space Sciences, University of California, Los Angeles, Los Angeles, California 90095, USA
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15
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Lapenta G, Berchem J, Alaoui ME, Walker R. Turbulent Energization of Electron Power Law Tails during Magnetic Reconnection. PHYSICAL REVIEW LETTERS 2020; 125:225101. [PMID: 33315458 DOI: 10.1103/physrevlett.125.225101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/21/2020] [Accepted: 10/20/2020] [Indexed: 06/12/2023]
Abstract
Earth's magnetotail is an excellent laboratory to study the interplay of reconnection and turbulence in determining electron energization. The process of formation of a power law tail during turbulent reconnection is a documented fact still in need of a comprehensive explanation. We conduct a massively parallel, particle in cell 3D simulation and use enhanced statistical resolution of the high energy range of the particle velocities to study how reconnection creates the conditions for the tail to be formed. The process is not direct acceleration by the coherent, laminar reconnection-generated electric field. Rather, reconnection causes turbulent outflows where energy exchange is dominated by a highly non-Gaussian distribution of fluctuations. Electron energization is diffuse throughout the entire reconnection outflow, but it is heightened by regions of intensified magnetic field such as dipolarization fronts traveling toward Earth.
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Affiliation(s)
- Giovanni Lapenta
- Department of Mathematics, KU Leuven, Leuven, Belgium and Space Science Institute, Boulder, Colorado, USA
| | - Jean Berchem
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547, USA
| | - Mostafa El Alaoui
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547, USA
| | - Raymond Walker
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095-1567, USA
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16
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Magnetotail reconnection onset caused by electron kinetics with a strong external driver. Nat Commun 2020; 11:5049. [PMID: 33028826 PMCID: PMC7542433 DOI: 10.1038/s41467-020-18787-w] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 09/08/2020] [Indexed: 12/02/2022] Open
Abstract
Magnetotail reconnection plays a crucial role in explosive energy conversion in geospace. Because of the lack of in-situ spacecraft observations, the onset mechanism of magnetotail reconnection, however, has been controversial for decades. The key question is whether magnetotail reconnection is externally driven to occur first on electron scales or spontaneously arising from an unstable configuration on ion scales. Here, we show, using spacecraft observations and particle-in-cell (PIC) simulations, that magnetotail reconnection starts from electron reconnection in the presence of a strong external driver. Our PIC simulations show that this electron reconnection then develops into ion reconnection. These results provide direct evidence for magnetotail reconnection onset caused by electron kinetics with a strong external driver. Magnetotail reconnection plays a crucial role in explosive energy conversion in geospace. Here, the authors show that magnetotail reconnection starts from electron reconnection in the presence of a strong external driver, which then develops into ion reconnection.
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17
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Argall MR, Small CR, Piatt S, Breen L, Petrik M, Kokkonen K, Barnum J, Larsen K, Wilder FD, Oka M, Paterson WR, Torbert RB, Ergun RE, Phan T, Giles BL, Burch JL. MMS SITL Ground Loop: Automating the Burst Data Selection Process. FRONTIERS IN ASTRONOMY AND SPACE SCIENCES 2020; 7:54. [PMID: 34712702 PMCID: PMC8549770 DOI: 10.3389/fspas.2020.00054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Global-scale energy flow throughout Earth's magnetosphere is catalyzed by processes that occur at Earth's magnetopause (MP). Magnetic reconnection is one process responsible for solar wind entry into and global convection within the magnetosphere, and the MP location, orientation, and motion have an impact on the dynamics. Statistical studies that focus on these and other MP phenomena and characteristics inherently require MP identification in their event search criteria, a task that can be automated using machine learning so that more man hours can be spent on research and analysis. We introduce a Long-Short Term Memory (LSTM) Recurrent Neural Network model to detect MP crossings and assist studies of energy transfer into the magnetosphere. As its first application, the LSTM has been implemented into the operational data stream of the Magnetospheric Multiscale (MMS) mission. MMS focuses on the electron diffusion region of reconnection, where electron dynamics break magnetic field lines and plasma is energized. MMS employs automated burst triggers onboard the spacecraft and a Scientist-in-the-Loop (SITL) on the ground to select intervals likely to contain diffusion regions. Only low-resolution survey data is available to the SITL, which is insufficient to resolve electron dynamics. A strategy for the SITL, then, is to select all MP crossings. Of all 219 SITL selections classified as MP crossings during the first five months of model operations, the model predicted 166 (76%) of them, and of all 360 model predictions, 257 (71%) were selected by the SITL. Most predictions that were not classified as MP crossings by the SITL were still MP-like, in that the intervals contained mixed magnetosheath and magnetospheric plasmas. The LSTM model and its predictions are public to ease the burden of arduous event searches involving the MP, including those for EDRs. For MMS, this helps free up mission operation costs by consolidating manual classification processes into automated routines.
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Affiliation(s)
- Matthew R. Argall
- Space Science Center, EOS, University of New Hampshire, Durham, NC, United States
| | - Colin R. Small
- Department of Computer Science, University of New Hampshire, Durham, NC, United States
| | - Samantha Piatt
- Department of Computer Science, University of New Hampshire, Durham, NC, United States
| | - Liam Breen
- Department of Computer Science, University of New Hampshire, Durham, NC, United States
| | - Marek Petrik
- Department of Computer Science, University of New Hampshire, Durham, NC, United States
| | - Kim Kokkonen
- Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder CO, United States
| | - Julie Barnum
- Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder CO, United States
| | - Kristopher Larsen
- Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder CO, United States
| | - Frederick D. Wilder
- Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder CO, United States
| | - Mitsuo Oka
- Space Science Laboratory, University of California at Berkeley, Berkeley, CA, United States
| | | | - Roy B. Torbert
- Space Science Center, EOS, University of New Hampshire, Durham, NC, United States
- EOS-SwRI, Southwest Research Institute, Durham, NH, United States
| | - Robert E. Ergun
- Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder CO, United States
| | - Tai Phan
- Space Science Laboratory, University of California at Berkeley, Berkeley, CA, United States
| | | | - James L. Burch
- Southwest Research Institute, San Antonio, TX, United States
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18
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Hwang K, Dokgo K, Choi E, Burch JL, Sibeck DG, Giles BL, Hasegawa H, Fu HS, Liu Y, Wang Z, Nakamura TKM, Ma X, Fear RC, Khotyaintsev Y, Graham DB, Shi QQ, Escoubet CP, Gershman DJ, Paterson WR, Pollock CJ, Ergun RE, Torbert RB, Dorelli JC, Avanov L, Russell CT, Strangeway RJ. Magnetic Reconnection Inside a Flux Rope Induced by Kelvin-Helmholtz Vortices. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2020; 125:e2019JA027665. [PMID: 32714734 PMCID: PMC7375157 DOI: 10.1029/2019ja027665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 01/29/2020] [Accepted: 03/03/2020] [Indexed: 06/11/2023]
Abstract
On 5 May 2017, MMS observed a crater-type flux rope on the dawnside tailward magnetopause with fluctuations. The boundary-normal analysis shows that the fluctuations can be attributed to nonlinear Kelvin-Helmholtz (KH) waves. Reconnection signatures such as flow reversals and Joule dissipation were identified at the leading and trailing edges of the flux rope. In particular, strong northward electron jets observed at the trailing edge indicated midlatitude reconnection associated with the 3-D structure of the KH vortex. The scale size of the flux rope, together with reconnection signatures, strongly supports the interpretation that the flux rope was generated locally by KH vortex-induced reconnection. The center of the flux rope also displayed signatures of guide-field reconnection (out-of-plane electron jets, parallel electron heating, and Joule dissipation). These signatures indicate that an interface between two interlinked flux tubes was undergoing interaction, causing a local magnetic depression, resulting in an M-shaped crater flux rope, as supported by reconstruction.
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Affiliation(s)
- K.‐J. Hwang
- Southwest Research InstituteSan AntonioTXUSA
| | - K. Dokgo
- Southwest Research InstituteSan AntonioTXUSA
| | - E. Choi
- Southwest Research InstituteSan AntonioTXUSA
| | - J. L. Burch
- Southwest Research InstituteSan AntonioTXUSA
| | | | - B. L. Giles
- NASA Goddard Space Flight CenterGreenbeltMDUSA
| | - H. Hasegawa
- Institute of Space and Astronautical ScienceJapan Aerospace Exploration AgencySagamiharaJapan
| | - H. S. Fu
- School of Science and EnvironmentBeihang UniversityBeijingChina
| | - Y. Liu
- School of Science and EnvironmentBeihang UniversityBeijingChina
| | - Z. Wang
- School of Science and EnvironmentBeihang UniversityBeijingChina
| | | | - X. Ma
- Physical Sciences DepartmentEmbry‐Riddle Aeronautical UniversityDaytona BeachFLUSA
| | - R. C. Fear
- School of Physics and AstronomyUniversity of SouthamptonSouthamptonUK
| | | | | | - Q. Q. Shi
- School of Earth and Space SciencesPeking UniversityPekingChina
| | - C. P. Escoubet
- European Space Research and Technology CentreNoordwijkthe Netherlands
| | | | | | | | - R. E. Ergun
- Laboratory for Atmospheric and Space PhysicsUniversity of Colorado at BoulderBoulderCOUSA
| | - R. B. Torbert
- Space Science CenterUniversity of New HampshireDurhamNHUSA
| | | | - L. Avanov
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- The Goddard Planetary Heliophysics InstituteUniversity of Maryland, Baltimore CountyBaltimoreMDUSA
| | - C. T. Russell
- Institute of Geophysics and Planetary PhysicsUniversity of California, Los AngelesLos AngelesCAUSA
| | - R. J. Strangeway
- Institute of Geophysics and Planetary PhysicsUniversity of California, Los AngelesLos AngelesCAUSA
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19
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Khotyaintsev YV, Graham DB, Steinvall K, Alm L, Vaivads A, Johlander A, Norgren C, Li W, Divin A, Fu HS, Hwang KJ, Burch JL, Ahmadi N, Le Contel O, Gershman DJ, Russell CT, Torbert RB. Electron Heating by Debye-Scale Turbulence in Guide-Field Reconnection. PHYSICAL REVIEW LETTERS 2020; 124:045101. [PMID: 32058767 DOI: 10.1103/physrevlett.124.045101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 11/22/2019] [Indexed: 06/10/2023]
Abstract
We report electrostatic Debye-scale turbulence developing within the diffusion region of asymmetric magnetopause reconnection with a moderate guide field using observations by the Magnetospheric Multiscale mission. We show that Buneman waves and beam modes cause efficient and fast thermalization of the reconnection electron jet by irreversible phase mixing, during which the jet kinetic energy is transferred into thermal energy. Our results show that the reconnection diffusion region in the presence of a moderate guide field is highly turbulent, and that electrostatic turbulence plays an important role in electron heating.
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Affiliation(s)
| | - D B Graham
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
| | - K Steinvall
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
| | - L Alm
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
| | - A Vaivads
- Department of Space and Plasma Physics, School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, Stockholm 11428, Sweden
| | - A Johlander
- Department of Physics, University of Helsinki, Helsinki 00014, Finland
| | - C Norgren
- University of Bergen, Bergen 5007, Norway
| | - W Li
- State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China
| | - A Divin
- Earth Physics Department, St. Petersburg State University, St. Petersburg 198504, Russia
| | - H S Fu
- School of Space and Environment, Beihang University, Beijing 100083, China
| | - K-J Hwang
- Southwest Research Institute, San Antonio, Texas 78228, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, Texas 78228, USA
| | - N Ahmadi
- Laboratory of Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - O Le Contel
- Laboratoire de Physique des Plasmas, CNRS, Ecole Polytechnique, Sorbonne Université, Université Paris-Sud, and Observatoire de Paris, Paris, F-75252 Paris Cedex 05, France
| | - D J Gershman
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - C T Russell
- University of California, Los Angeles, California 90095, USA
| | - R B Torbert
- University of New Hampshire, Durham, New Hampshire 03824, USA
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20
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Egedal J, Ng J, Le A, Daughton W, Wetherton B, Dorelli J, Gershman D, Rager A. Pressure Tensor Elements Breaking the Frozen-In Law During Reconnection in Earth's Magnetotail. PHYSICAL REVIEW LETTERS 2019; 123:225101. [PMID: 31868399 DOI: 10.1103/physrevlett.123.225101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 08/22/2019] [Indexed: 06/10/2023]
Abstract
Aided by fully kinetic simulations, spacecraft observations of magnetic reconnection in Earth's magnetotail are analyzed. The structure of the electron diffusion region is in quantitative agreement with the numerical model. Of special interest, the spacecraft data reveal how reconnection is mediated by off-diagonal stress in the electron pressure tensor breaking the frozen-in law of the electron fluid.
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Affiliation(s)
- J Egedal
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - J Ng
- Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - A Le
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - W Daughton
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - B Wetherton
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - J Dorelli
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - D Gershman
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - A Rager
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
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21
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Mechanism of Reconnection on Kinetic Scales Based on Magnetospheric Multiscale Mission Observations. ACTA ACUST UNITED AC 2019. [DOI: 10.3847/2041-8213/ab4b5a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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22
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Hwang K, Choi E, Dokgo K, Burch JL, Sibeck DG, Giles BL, Goldstein ML, Paterson WR, Pollock CJ, Shi QQ, Fu H, Hasegawa H, Gershman DJ, Khotyaintsev Y, Torbert RB, Ergun RE, Dorelli JC, Avanov L, Russell CT, Strangeway RJ. Electron Vorticity Indicative of the Electron Diffusion Region of Magnetic Reconnection. GEOPHYSICAL RESEARCH LETTERS 2019; 46:6287-6296. [PMID: 31598018 PMCID: PMC6774273 DOI: 10.1029/2019gl082710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/08/2019] [Accepted: 05/28/2019] [Indexed: 06/10/2023]
Abstract
While vorticity defined as the curl of the velocity has been broadly used in fluid and plasma physics, this quantity has been underutilized in space physics due to low time resolution observations. We report Magnetospheric Multiscale (MMS) observations of enhanced electron vorticity in the vicinity of the electron diffusion region of magnetic reconnection. On 11 July 2017 MMS traversed the magnetotail current sheet, observing tailward-to-earthward outflow reversal, current-carrying electron jets in the direction along the electron meandering motion or out-of-plane direction, agyrotropic electron distribution functions, and dissipative signatures. At the edge of the electron jets, the electron vorticity increased with magnitudes greater than the electron gyrofrequency. The out-of-plane velocity shear along distance from the current sheet leads to the enhanced vorticity. This, in turn, contributes to the magnetic field perturbations observed by MMS. These observations indicate that electron vorticity can act as a proxy for delineating the electron diffusion region of magnetic reconnection.
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Affiliation(s)
- K.‐J. Hwang
- Southwest Research InstituteSan AntonioTXUSA
| | - E. Choi
- Southwest Research InstituteSan AntonioTXUSA
| | - K. Dokgo
- Southwest Research InstituteSan AntonioTXUSA
| | - J. L. Burch
- Southwest Research InstituteSan AntonioTXUSA
| | | | - B. L. Giles
- NASA Goddard Space Flight CenterGreenbeltMDUSA
| | - M. L. Goldstein
- The Goddard Planetary Heliophysics InstituteUniversity of MarylandBaltimoreMDUSA
| | | | | | - Q. Q. Shi
- School of Earth and Space SciencesPeking UniversityPekingChina
| | - H. Fu
- School of Science and EnvironmentBeihang UniversityBeijingChina
| | - H. Hasegawa
- Institute of Space and Astronautical ScienceJapan Aerospace Exploration AgencySagamiharaJapan
| | | | | | - R. B. Torbert
- Space Science CenterUniversity of New HampshireDurhamNHUSA
| | - R. E. Ergun
- Laboratory for Atmospheric and Space PhysicsUniversity of Colorado BoulderBoulderCOUSA
| | | | - L. Avanov
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- The Goddard Planetary Heliophysics InstituteUniversity of MarylandBaltimoreMDUSA
| | - C. T. Russell
- Institute of Geophysics and Planetary PhysicsUniversity of CaliforniaLos AngelesCAUSA
| | - R. J. Strangeway
- Institute of Geophysics and Planetary PhysicsUniversity of CaliforniaLos AngelesCAUSA
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23
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Sitnov M, Birn J, Ferdousi B, Gordeev E, Khotyaintsev Y, Merkin V, Motoba T, Otto A, Panov E, Pritchett P, Pucci F, Raeder J, Runov A, Sergeev V, Velli M, Zhou X. Explosive Magnetotail Activity. SPACE SCIENCE REVIEWS 2019; 215:31. [PMID: 31178609 PMCID: PMC6528807 DOI: 10.1007/s11214-019-0599-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 04/27/2019] [Indexed: 06/01/2023]
Abstract
Modes and manifestations of the explosive activity in the Earth's magnetotail, as well as its onset mechanisms and key pre-onset conditions are reviewed. Two mechanisms for the generation of the pre-onset current sheet are discussed, namely magnetic flux addition to the tail lobes, or other high-latitude perturbations, and magnetic flux evacuation from the near-Earth tail associated with dayside reconnection. Reconnection onset may require stretching and thinning of the sheet down to electron scales. It may also start in thicker sheets in regions with a tailward gradient of the equatorial magnetic field B z ; in this case it begins as an ideal-MHD instability followed by the generation of bursty bulk flows and dipolarization fronts. Indeed, remote sensing and global MHD modeling show the formation of tail regions with increased B z , prone to magnetic reconnection, ballooning/interchange and flapping instabilities. While interchange instability may also develop in such thicker sheets, it may grow more slowly compared to tearing and cause secondary reconnection locally in the dawn-dusk direction. Post-onset transients include bursty flows and dipolarization fronts, micro-instabilities of lower-hybrid-drift and whistler waves, as well as damped global flux tube oscillations in the near-Earth region. They convert the stretched tail magnetic field energy into bulk plasma acceleration and collisionless heating, excitation of a broad spectrum of plasma waves, and collisional dissipation in the ionosphere. Collisionless heating involves ion reflection from fronts, Fermi, betatron as well as other, non-adiabatic, mechanisms. Ionospheric manifestations of some of these magnetotail phenomena are discussed. Explosive plasma phenomena observed in the laboratory, the solar corona and solar wind are also discussed.
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Affiliation(s)
- Mikhail Sitnov
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD USA
| | | | | | - Evgeny Gordeev
- Earth’s Physics Department, Saint Petersburg State University, St. Petersburg, Russia
| | | | - Viacheslav Merkin
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD USA
| | - Tetsuo Motoba
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD USA
| | | | - Evgeny Panov
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - Philip Pritchett
- Department of Physics and Astronomy, University of California, Los Angeles, CA USA
| | - Fulvia Pucci
- National Institute for Fusion Science, National Institutes of Natural Sciences, Toki, 509-5292 Japan
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ USA
| | - Joachim Raeder
- Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH USA
| | - Andrei Runov
- Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA USA
| | - Victor Sergeev
- Earth’s Physics Department, Saint Petersburg State University, St. Petersburg, Russia
| | - Marco Velli
- University of California Los Angeles, Los Angeles, CA 90095 USA
| | - Xuzhi Zhou
- School of Earth and Space Sciences, Peking University, Beijing, 100871 China
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24
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Nakamura R, Genestreti KJ, Nakamura T, Baumjohann W, Varsani A, Nagai T, Bessho N, Burch JL, Denton RE, Eastwood JP, Ergun RE, Gershman DJ, Giles BL, Hasegawa H, Hesse M, Lindqvist P, Russell CT, Stawarz JE, Strangeway RJ, Torbert RB. Structure of the Current Sheet in the 11 July 2017 Electron Diffusion Region Event. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2019; 124:1173-1186. [PMID: 31008008 PMCID: PMC6472497 DOI: 10.1029/2018ja026028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 12/16/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
Abstract
The structure of the current sheet along the Magnetospheric Multiscale (MMS) orbit is examined during the 11 July 2017 Electron Diffusion Region (EDR) event. The location of MMS relative to the X-line is deduced and used to obtain the spatial changes in the electron parameters. The electron velocity gradient values are used to estimate the reconnection electric field sustained by nongyrotropic pressure. It is shown that the observations are consistent with theoretical expectations for an inner EDR in 2-D reconnection. That is, the magnetic field gradient scale, where the electric field due to electron nongyrotropic pressure dominates, is comparable to the gyroscale of the thermal electrons at the edge of the inner EDR. Our approximation of the MMS observations using a steady state, quasi-2-D, tailward retreating X-line was valid only for about 1.4 s. This suggests that the inner EDR is localized; that is, electron outflow jet braking takes place within an ion inertia scale from the X-line. The existence of multiple events or current sheet processes outside the EDR may play an important role in the geometry of reconnection in the near-Earth magnetotail.
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Affiliation(s)
- Rumi Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - Kevin J. Genestreti
- Space Research InstituteAustrian Academy of SciencesGrazAustria
- Space Science CenterUniversity New HampshireDurhamNHUSA
| | - Takuma Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | | | - Ali Varsani
- Mullard Space Science LaboratoryUniversity College LondonDorkingUK
| | - Tsugunobu Nagai
- Institute of Space and Astronautical ScienceJapan Aerospace Exploration AgencySagamiharaJapan
| | | | | | | | | | - Robert E. Ergun
- Department of Astrophysical and Planetary SciencesUniversity of Colorado BoulderBoulderCOUSA
| | | | | | - Hiroshi Hasegawa
- Institute of Space and Astronautical ScienceJapan Aerospace Exploration AgencySagamiharaJapan
| | - Michael Hesse
- Department of Physics and TechnologyUniversity of BergenBergenNorway
| | | | - Christopher T. Russell
- Department of Earth, Planetary, and Space SciencesUniversity of California, Los AngelesLos AngelesCAUSA
| | | | - Robert J. Strangeway
- Department of Earth, Planetary, and Space SciencesUniversity of California, Los AngelesLos AngelesCAUSA
| | - Roy B. Torbert
- Space Science CenterUniversity New HampshireDurhamNHUSA
- Southwest Research InstituteSan AntonioTXUSA
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25
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Genestreti KJ, Nakamura TKM, Nakamura R, Denton RE, Torbert RB, Burch JL, Plaschke F, Fuselier SA, Ergun RE, Giles BL, Russell CT. How Accurately Can We Measure the Reconnection Rate E M for the MMS Diffusion Region Event of 11 July 2017? JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2018; 123:9130-9149. [PMID: 30775197 PMCID: PMC6360497 DOI: 10.1029/2018ja025711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 08/10/2018] [Accepted: 09/11/2018] [Indexed: 06/09/2023]
Abstract
We investigate the accuracy with which the reconnection electric field E M can be determined from in situ plasma data. We study the magnetotail electron diffusion region observed by National Aeronautics and Space Administration's Magnetospheric Multiscale (MMS) on 11 July 2017 at 22:34 UT and focus on the very large errors in E M that result from errors in an L M N boundary normal coordinate system. We determine several L M N coordinates for this MMS event using several different methods. We use these M axes to estimate E M. We find some consensus that the reconnection rate was roughly E M = 3.2 ± 0.6 mV/m, which corresponds to a normalized reconnection rate of 0.18 ± 0.035. Minimum variance analysis of the electron velocity (MVA-v e), MVA of E, minimization of Faraday residue, and an adjusted version of the maximum directional derivative of the magnetic field (MDD-B) technique all produce reasonably similar coordinate axes. We use virtual MMS data from a particle-in-cell simulation of this event to estimate the errors in the coordinate axes and reconnection rate associated with MVA-v e and MDD-B. The L and M directions are most reliably determined by MVA-v e when the spacecraft observes a clear electron jet reversal. When the magnetic field data have errors as small as 0.5% of the background field strength, the M direction obtained by MDD-B technique may be off by as much as 35°. The normal direction is most accurately obtained by MDD-B. Overall, we find that these techniques were able to identify E M from the virtual data within error bars ≥20%.
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Affiliation(s)
- K. J. Genestreti
- Space Research InstituteAustrian Academy of SciencesGrazAustria
- Now at Space Science CenterUniversity of New HampshireDurhamNHUSA
| | | | - R. Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - R. E. Denton
- Department of Physics and AstronomyDartmouth CollegeHanoverNHUSA
| | - R. B. Torbert
- Space Science CenterUniversity of New HampshireDurhamNHUSA
- Space Science and Engineering DivisionSouthwest Research InstituteSan AntonioTXUSA
| | - J. L. Burch
- Space Science and Engineering DivisionSouthwest Research InstituteSan AntonioTXUSA
| | - F. Plaschke
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | - S. A. Fuselier
- Space Science and Engineering DivisionSouthwest Research InstituteSan AntonioTXUSA
- Department of Physics and AstronomyUniversity of Texas at San AntonioSan AntonioTXUSA
| | - R. E. Ergun
- Laboratory of Atmospheric and Space SciencesUniversity of Colorado BoulderBoulderCOUSA
| | - B. L. Giles
- Heliophysics Science DivisionNASA Goddard Space Flight CenterGreenbeltMDUSA
| | - C. T. Russell
- Institute of Geophysics and Planetary PhysicsUniversity of CaliforniaLos AngelesCAUSA
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