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Wang S, Lu S, Lu Q, Wang R, Ren J, Gao X, Guo J. Origin of reconnecting current sheets in shocked turbulent plasma. SCIENCE ADVANCES 2024; 10:eado4639. [PMID: 39141737 PMCID: PMC11323938 DOI: 10.1126/sciadv.ado4639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Accepted: 07/10/2024] [Indexed: 08/16/2024]
Abstract
Magnetic reconnection, the rearrangement of magnetic field topologies, is a fundamental plasma process throughout the universe, which converts magnetic energy to plasma kinetic energy and results in particle energization. A current sheet is a prerequisite for the occurrence of magnetic reconnection. It has been well documented that reconnecting current sheets are prevalent in turbulent plasmas. However, how these current sheets are formed remains unclear. Among natural plasmas, the region downstream of the Earth's bow shock, the magnetosheath, is one of the most turbulent. Here, we show that the reconnecting current sheets in the turbulent magnetosheath originate from the waves in the region upstream of the shock. Once excited, the upstream waves are transmitted across the shock, compressed, and then transformed into current sheets in the downstream region. Magnetic reconnection subsequently occurs in these downstream current sheets. This process can be generalized to various shocked plasmas in astrophysical and laboratorial environments where turbulent magnetic reconnection should be common.
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Affiliation(s)
- Shimou Wang
- Deep Space Exploration Laboratory/School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- CAS Center for Excellence in Comparative Planetology/CAS Key Lab of Geospace Environment, University of Science and Technology of China, Hefei, Anhui, China
- Collaborative Innovation Center of Astronautical Science and Technology, Harbin, Heilongjiang, China
| | - San Lu
- Deep Space Exploration Laboratory/School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- CAS Center for Excellence in Comparative Planetology/CAS Key Lab of Geospace Environment, University of Science and Technology of China, Hefei, Anhui, China
- Collaborative Innovation Center of Astronautical Science and Technology, Harbin, Heilongjiang, China
| | - Quanming Lu
- Deep Space Exploration Laboratory/School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- CAS Center for Excellence in Comparative Planetology/CAS Key Lab of Geospace Environment, University of Science and Technology of China, Hefei, Anhui, China
- Collaborative Innovation Center of Astronautical Science and Technology, Harbin, Heilongjiang, China
| | - Rongsheng Wang
- Deep Space Exploration Laboratory/School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- CAS Center for Excellence in Comparative Planetology/CAS Key Lab of Geospace Environment, University of Science and Technology of China, Hefei, Anhui, China
- Collaborative Innovation Center of Astronautical Science and Technology, Harbin, Heilongjiang, China
| | - Junyi Ren
- Deep Space Exploration Laboratory/School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- CAS Center for Excellence in Comparative Planetology/CAS Key Lab of Geospace Environment, University of Science and Technology of China, Hefei, Anhui, China
- Collaborative Innovation Center of Astronautical Science and Technology, Harbin, Heilongjiang, China
| | - Xinliang Gao
- Deep Space Exploration Laboratory/School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- CAS Center for Excellence in Comparative Planetology/CAS Key Lab of Geospace Environment, University of Science and Technology of China, Hefei, Anhui, China
- Collaborative Innovation Center of Astronautical Science and Technology, Harbin, Heilongjiang, China
| | - Jin Guo
- Deep Space Exploration Laboratory/School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui, China
- CAS Center for Excellence in Comparative Planetology/CAS Key Lab of Geospace Environment, University of Science and Technology of China, Hefei, Anhui, China
- Collaborative Innovation Center of Astronautical Science and Technology, Harbin, Heilongjiang, China
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2
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Hasegawa H, Denton RE, Dokgo K, Hwang K, Nakamura TKM, Burch JL. Ion-Scale Magnetic Flux Rope Generated From Electron-Scale Magnetopause Current Sheet: Magnetospheric Multiscale Observations. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2023; 128:e2022JA031092. [PMID: 38440152 PMCID: PMC10909477 DOI: 10.1029/2022ja031092] [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: 10/17/2022] [Revised: 03/05/2023] [Accepted: 03/08/2023] [Indexed: 03/06/2024]
Abstract
We present in-depth analysis of three southward-moving meso-scale (ion-to magnetohydrodynamic-scale) flux transfer events (FTEs) and subsequent crossing of a reconnecting magnetopause current sheet (MPCS), which were observed on 8 December 2015 by the Magnetospheric Multiscale spacecraft in the subsolar region under southward and duskward magnetosheath magnetic field conditions. We aim to understand the generation mechanism of ion-scale magnetic flux ropes (ISFRs) and to reveal causal relationship among magnetic field structures, electromagnetic energy conversion, and kinetic processes in magnetic reconnection layers. Results from magnetic field reconstruction methods are consistent with a flux rope with a length of about one ion inertial length growing from an electron-scale current sheet (ECS) in the MPCS, supporting the idea that ISFRs can be generated through secondary reconnection in an ECS. Grad-Shafranov reconstruction applied to the three FTEs shows that the FTEs had axial orientations similar to that of the ISFR. This suggests that these FTEs also formed through the same secondary reconnection process, rather than multiple X-line reconnection at spatially separated locations. Four-spacecraft observations of electron pitch-angle distributions and energy conversion rate j · E ' = j · E + v e × B suggest that the ISFR had three-dimensional magnetic topology and secondary reconnection was patchy or bursty. Previously reported positive and negative values of j · E ' , with magnitudes much larger than expected for typical MP reconnection, were seen in both magnetosheath and magnetospheric separatrix regions of the ISFR. Many of them coexisted with bi-directional electron beams and intense electric field fluctuations around the electron gyrofrequency, consistent with their origin in separatrix activities.
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Affiliation(s)
- H. Hasegawa
- Institute of Space and Astronautical ScienceJapan Aerospace Exploration AgencySagamiharaJapan
- Southwest Research InstituteSan AntonioTXUSA
| | - R. E. Denton
- Department of Physics and AstronomyDartmouth CollegeHanoverNHUSA
| | - K. Dokgo
- Southwest Research InstituteSan AntonioTXUSA
| | - K.‐J. Hwang
- Southwest Research InstituteSan AntonioTXUSA
| | | | - J. L. Burch
- Southwest Research InstituteSan AntonioTXUSA
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3
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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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4
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Eastwood JP, Mistry R, Phan TD, Schwartz SJ, Ergun RE, Drake JF, Øieroset M, Stawarz JE, Goldman MV, Haggerty C, Shay MA, Burch JL, Gershman DJ, Giles BL, Lindqvist PA, Torbert RB, Strangeway RJ, Russell CT. Guide Field Reconnection: Exhaust Structure and Heating. GEOPHYSICAL RESEARCH LETTERS 2018; 45:4569-4577. [PMID: 31031447 PMCID: PMC6473590 DOI: 10.1029/2018gl077670] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/11/2018] [Accepted: 04/14/2018] [Indexed: 06/09/2023]
Abstract
Magnetospheric Multiscale observations are used to probe the structure and temperature profile of a guide field reconnection exhaust ~100 ion inertial lengths downstream from the X-line in the Earth's magnetosheath. Asymmetric Hall electric and magnetic field signatures were detected, together with a density cavity confined near 1 edge of the exhaust and containing electron flow toward the X-line. Electron holes were also detected both on the cavity edge and at the Hall magnetic field reversal. Predominantly parallel ion and electron heating was observed in the main exhaust, but within the cavity, electron cooling and enhanced parallel ion heating were found. This is explained in terms of the parallel electric field, which inhibits electron mixing within the cavity on newly reconnected field lines but accelerates ions. Consequently, guide field reconnection causes inhomogeneous changes in ion and electron temperature across the exhaust.
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Affiliation(s)
| | - R. Mistry
- The Blackett LaboratoryImperial College LondonLondonUK
| | - T. D. Phan
- Space Sciences LaboratoryUniversity of CaliforniaBerkeleyCAUSA
| | - S. J. Schwartz
- The Blackett LaboratoryImperial College LondonLondonUK
- LASP/Department of Astrophysical and Planetary SciencesUniversity of Colorado BoulderBoulderCOUSA
| | - R. E. Ergun
- LASP/Department of Astrophysical and Planetary SciencesUniversity of Colorado BoulderBoulderCOUSA
| | - J. F. Drake
- Department of Physics and Institute for Physical Science and TechnologyUniversity of MarylandCollege ParkMDUSA
| | - M. Øieroset
- Space Sciences LaboratoryUniversity of CaliforniaBerkeleyCAUSA
| | - J. E. Stawarz
- The Blackett LaboratoryImperial College LondonLondonUK
| | - M. V. Goldman
- Department of PhysicsUniversity of Colorado BoulderBoulderCOUSA
| | - C. Haggerty
- Department of Physics and AstronomyUniversity of DelawareNewarkDEUSA
- Now at The Department of Astronomy and AstrophysicsUniversity of ChicagoChicagoILUSA
| | - M. A. Shay
- Department of Physics and AstronomyUniversity of DelawareNewarkDEUSA
| | - J. L. Burch
- Southwest Research InstituteSan AntonioTXUSA
| | - D. J. Gershman
- Department of Physics and AstronomyUniversity of DelawareNewarkDEUSA
- NASA Goddard Space Flight CenterGreenbeltMDUSA
| | - B. L. Giles
- NASA Goddard Space Flight CenterGreenbeltMDUSA
| | - P. A. Lindqvist
- Department of Space and Plasma PhysicsRoyal Institute of TechnologyStockholmSweden
| | - R. B. Torbert
- Now at The Department of Astronomy and AstrophysicsUniversity of ChicagoChicagoILUSA
- Space Science CenterUniversity of New HampshireDurhamNHUSA
| | - R. J. Strangeway
- Department of Earth, Planetary, and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - C. T. Russell
- Department of Earth, Planetary, and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
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5
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Howes GG. A prospectus on kinetic heliophysics. PHYSICS OF PLASMAS 2017; 24:055907. [PMID: 29104421 PMCID: PMC5648573 DOI: 10.1063/1.4983993] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/01/2017] [Indexed: 05/29/2023]
Abstract
Under the low density and high temperature conditions typical of heliospheric plasmas, the macroscopic evolution of the heliosphere is strongly affected by the kinetic plasma physics governing fundamental microphysical mechanisms. Kinetic turbulence, collisionless magnetic reconnection, particle acceleration, and kinetic instabilities are four poorly understood, grand-challenge problems that lie at the new frontier of kinetic heliophysics. The increasing availability of high cadence and high phase-space resolution measurements of particle velocity distributions by current and upcoming spacecraft missions and of massively parallel nonlinear kinetic simulations of weakly collisional heliospheric plasmas provides the opportunity to transform our understanding of these kinetic mechanisms through the full utilization of the information contained in the particle velocity distributions. Several major considerations for future investigations of kinetic heliophysics are examined. Turbulent dissipation followed by particle heating is highlighted as an inherently two-step process in weakly collisional plasmas, distinct from the more familiar case in fluid theory. Concerted efforts must be made to tackle the big-data challenge of visualizing the high-dimensional (3D-3V) phase space of kinetic plasma theory through physics-based reductions. Furthermore, the development of innovative analysis methods that utilize full velocity-space measurements, such as the field-particle correlation technique, will enable us to gain deeper insight into these four grand-challenge problems of kinetic heliophysics. A systems approach to tackle the multi-scale problem of heliophysics through a rigorous connection between the kinetic physics at microscales and the self-consistent evolution of the heliosphere at macroscales will propel the field of kinetic heliophysics into the future.
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Affiliation(s)
- Gregory G Howes
- Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA
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6
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Eriksson S, Wilder FD, Ergun RE, Schwartz SJ, Cassak PA, Burch JL, Chen LJ, Torbert RB, Phan TD, Lavraud B, Goodrich KA, Holmes JC, Stawarz JE, Sturner AP, Malaspina DM, Usanova ME, Trattner KJ, Strangeway RJ, Russell CT, Pollock CJ, Giles BL, Hesse M, Lindqvist PA, Drake JF, Shay MA, Nakamura R, Marklund GT. Magnetospheric Multiscale Observations of the Electron Diffusion Region of Large Guide Field Magnetic Reconnection. PHYSICAL REVIEW LETTERS 2016; 117:015001. [PMID: 27419573 DOI: 10.1103/physrevlett.117.015001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Indexed: 06/06/2023]
Abstract
We report observations from the Magnetospheric Multiscale (MMS) satellites of a large guide field magnetic reconnection event. The observations suggest that two of the four MMS spacecraft sampled the electron diffusion region, whereas the other two spacecraft detected the exhaust jet from the event. The guide magnetic field amplitude is approximately 4 times that of the reconnecting field. The event is accompanied by a significant parallel electric field (E_{∥}) that is larger than predicted by simulations. The high-speed (∼300 km/s) crossing of the electron diffusion region limited the data set to one complete electron distribution inside of the electron diffusion region, which shows significant parallel heating. The data suggest that E_{∥} is balanced by a combination of electron inertia and a parallel gradient of the gyrotropic electron pressure.
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Affiliation(s)
- S Eriksson
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - F D Wilder
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - R E Ergun
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - S J Schwartz
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- The Blackett Laboratory, Imperial College, London SW7 2AZ, United Kingdom
| | - P A Cassak
- West Virginia University, Morgantown, West Virginia 26506, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, Texas 78238-5166, USA
| | - L-J Chen
- University of Maryland, College Park, Maryland 20742, USA
| | - R B Torbert
- Southwest Research Institute, San Antonio, Texas 78238-5166, USA
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - T D Phan
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
| | - B Lavraud
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, 31028 Toulouse, France
- Centre National de la Recherche Scientifique, UMR 5277, Toulouse, France
| | - K A Goodrich
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - J C Holmes
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - J E Stawarz
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - A P Sturner
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - D M Malaspina
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - M E Usanova
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - K J Trattner
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - R J Strangeway
- University of California, Los Angeles, Los Angeles, California 90095, USA
| | - C T Russell
- University of California, Los Angeles, Los Angeles, California 90095, USA
| | - C J Pollock
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - B L Giles
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - M Hesse
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - P-A Lindqvist
- KTH Royal Institute of Technology, SE-11428 Stockholm, Sweden
| | - J F Drake
- University of Maryland, College Park, Maryland 20742, USA
| | - M A Shay
- University of Delaware, Newark, Delaware 19716, USA
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, 8042 Graz, Austria
| | - G T Marklund
- KTH Royal Institute of Technology, SE-11428 Stockholm, Sweden
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7
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Ergun RE, Goodrich KA, Wilder FD, Holmes JC, Stawarz JE, Eriksson S, Sturner AP, Malaspina DM, Usanova ME, Torbert RB, Lindqvist PA, Khotyaintsev Y, Burch JL, Strangeway RJ, Russell CT, Pollock CJ, Giles BL, Hesse M, Chen LJ, Lapenta G, Goldman MV, Newman DL, Schwartz SJ, Eastwood JP, Phan TD, Mozer FS, Drake J, Shay MA, Cassak PA, Nakamura R, Marklund G. Magnetospheric Multiscale Satellites Observations of Parallel Electric Fields Associated with Magnetic Reconnection. PHYSICAL REVIEW LETTERS 2016; 116:235102. [PMID: 27341241 DOI: 10.1103/physrevlett.116.235102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Indexed: 06/06/2023]
Abstract
We report observations from the Magnetospheric Multiscale satellites of parallel electric fields (E_{∥}) associated with magnetic reconnection in the subsolar region of the Earth's magnetopause. E_{∥} events near the electron diffusion region have amplitudes on the order of 100 mV/m, which are significantly larger than those predicted for an antiparallel reconnection electric field. This Letter addresses specific types of E_{∥} events, which appear as large-amplitude, near unipolar spikes that are associated with tangled, reconnected magnetic fields. These E_{∥} events are primarily in or near a current layer near the separatrix and are interpreted to be double layers that may be responsible for secondary reconnection in tangled magnetic fields or flux ropes. These results are telling of the three-dimensional nature of magnetopause reconnection and indicate that magnetopause reconnection may be often patchy and/or drive turbulence along the separatrix that results in flux ropes and/or tangled magnetic fields.
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Affiliation(s)
- R E Ergun
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - K A Goodrich
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - F D Wilder
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - J C Holmes
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - J E Stawarz
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - S Eriksson
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - A P Sturner
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - D M Malaspina
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - M E Usanova
- Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80303, USA
| | - R B Torbert
- University of New Hampshire, Durham, New Hampshire 03824, USA
- Southwest Research Institute, San Antonio, Texas 78238, USA
| | - P-A Lindqvist
- KTH Royal Institute of Technology, Stockholm, Sweden
| | - Y Khotyaintsev
- Swedish Institute of Space Physics (Uppsala), Uppsala, Sweden
| | - J L Burch
- Southwest Research Institute, San Antonio, Texas 78238, USA
| | - R J Strangeway
- University of California, Los Angeles, Los Angeles, California 90095, USA
| | - C T Russell
- University of California, Los Angeles, Los Angeles, California 90095, USA
| | - C J Pollock
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - B L Giles
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - M Hesse
- NASA, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - L J Chen
- University of Maryland, College Park, Maryland 20742, USA
| | - G Lapenta
- Leuven Universiteit, Leuven, Belgium
| | - M V Goldman
- Department of Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - D L Newman
- Department of Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - S J Schwartz
- Laboratory of Atmospheric and Space Sciences, University of Colorado, Boulder, Colorado 80303, USA
- The Blackett Laboratory, Imperial College London, United Kingdom
| | - J P Eastwood
- The Blackett Laboratory, Imperial College London, United Kingdom
| | - T D Phan
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
| | - F S Mozer
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
| | - J Drake
- University of Maryland, College Park, Maryland 20742, USA
| | - M A Shay
- University of Delaware, Newark, Delaware 19716, USA
| | - P A Cassak
- West Virginia University, Morgantown, West Virginia 26506, USA
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - G Marklund
- KTH Royal Institute of Technology, Stockholm, Sweden
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8
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Howes GG. A dynamical model of plasma turbulence in the solar wind. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:20140145. [PMID: 25848075 PMCID: PMC4394677 DOI: 10.1098/rsta.2014.0145] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/05/2015] [Indexed: 06/01/2023]
Abstract
A dynamical approach, rather than the usual statistical approach, is taken to explore the physical mechanisms underlying the nonlinear transfer of energy, the damping of the turbulent fluctuations, and the development of coherent structures in kinetic plasma turbulence. It is argued that the linear and nonlinear dynamics of Alfvén waves are responsible, at a very fundamental level, for some of the key qualitative features of plasma turbulence that distinguish it from hydrodynamic turbulence, including the anisotropic cascade of energy and the development of current sheets at small scales. The first dynamical model of kinetic turbulence in the weakly collisional solar wind plasma that combines self-consistently the physics of Alfvén waves with the development of small-scale current sheets is presented and its physical implications are discussed. This model leads to a simplified perspective on the nature of turbulence in a weakly collisional plasma: the nonlinear interactions responsible for the turbulent cascade of energy and the formation of current sheets are essentially fluid in nature, while the collisionless damping of the turbulent fluctuations and the energy injection by kinetic instabilities are essentially kinetic in nature.
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Affiliation(s)
- G G Howes
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA
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9
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Liu YH, Guo F, Daughton W, Li H, Hesse M. Scaling of magnetic reconnection in relativistic collisionless pair plasmas. PHYSICAL REVIEW LETTERS 2015; 114:095002. [PMID: 25793820 DOI: 10.1103/physrevlett.114.095002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Indexed: 06/04/2023]
Abstract
Using fully kinetic simulations, we study the scaling of the inflow speed of collisionless magnetic reconnection in electron-positron plasmas from the nonrelativistic to ultrarelativistic limit. In the antiparallel configuration, the inflow speed increases with the upstream magnetization parameter σ and approaches the speed of light when σ>O(100), leading to an enhanced reconnection rate. In all regimes, the divergence of the pressure tensor is the dominant term responsible for breaking the frozen-in condition at the x line. The observed scaling agrees well with a simple model that accounts for the Lorentz contraction of the plasma passing through the diffusion region. The results demonstrate that the aspect ratio of the diffusion region, modified by the compression factor of proper density, remains ∼0.1 in both the nonrelativistic and relativistic limits.
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Affiliation(s)
- Yi-Hsin Liu
- NASA-Goddard Space Flight Center, Greenbelt, Maryland 20771, 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
| | - Michael Hesse
- NASA-Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
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10
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Tharp TD, Yamada M, Ji H, Lawrence E, Dorfman S, Myers CE, Yoo J. Quantitative study of guide-field effects on Hall reconnection in a laboratory plasma. PHYSICAL REVIEW LETTERS 2012; 109:165002. [PMID: 23215088 DOI: 10.1103/physrevlett.109.165002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 09/17/2012] [Indexed: 06/01/2023]
Abstract
The effect of guide field on magnetic reconnection is quantitatively studied by systematically varying an applied guide field in the Magnetic Reconnection Experiment (MRX). The quadrupole field, a signature of two-fluid reconnection at zero guide field, is altered by a finite guide field. It is shown that the reconnection rate is significantly reduced with increasing guide field, and this dependence is explained by a combination of local and global physics: locally, the in-plane Hall currents are reduced, while globally guide field compression produces an increased pressure both within and downstream of the reconnection region.
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Affiliation(s)
- T D Tharp
- Center for Magnetic Self-Organization and Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08540, USA
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11
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A current filamentation mechanism for breaking magnetic field lines during reconnection. Nature 2011; 474:184-7. [PMID: 21633355 DOI: 10.1038/nature10091] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Accepted: 04/01/2011] [Indexed: 11/09/2022]
Abstract
During magnetic reconnection, the field lines must break and reconnect to release the energy that drives solar and stellar flares and other explosive events in space and in the laboratory. Exactly how this happens has been unclear, because dissipation is needed to break magnetic field lines and classical collisions are typically weak. Ion-electron drag arising from turbulence, dubbed 'anomalous resistivity', and thermal momentum transport are two mechanisms that have been widely invoked. Measurements of enhanced turbulence near reconnection sites in space and in the laboratory support the anomalous resistivity idea but there has been no demonstration from measurements that this turbulence produces the necessary enhanced drag. Here we report computer simulations that show that neither of the two previously favoured mechanisms controls how magnetic field lines reconnect in the plasmas of greatest interest, those in which the magnetic field dominates the energy budget. Rather, we find that when the current layers that form during magnetic reconnection become too intense, they disintegrate and spread into a complex web of filaments that causes the rate of reconnection to increase abruptly. This filamentary web can be explored in the laboratory or in space with satellites that can measure the resulting electromagnetic turbulence.
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12
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Zenitani S, Hesse M, Klimas A, Kuznetsova M. New measure of the dissipation region in collisionless magnetic reconnection. PHYSICAL REVIEW LETTERS 2011; 106:195003. [PMID: 21668168 DOI: 10.1103/physrevlett.106.195003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Indexed: 05/30/2023]
Abstract
A new measure to identify a small-scale dissipation region in collisionless magnetic reconnection is proposed. The energy transfer from the electromagnetic field to plasmas in the electron's rest frame is formulated as a Lorentz-invariant scalar quantity. The measure is tested by two-dimensional particle-in-cell simulations in typical configurations: symmetric and asymmetric reconnection, with and without the guide field. The innermost region surrounding the reconnection site is accurately located in all cases. We further discuss implications for nonideal MHD dissipation.
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Affiliation(s)
- Seiji Zenitani
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
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13
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Lu Q, Wang R, Xie J, Huang C, Lu S, Wang S. Electron dynamics in collisionless magnetic reconnection. CHINESE SCIENCE BULLETIN-CHINESE 2011. [DOI: 10.1007/s11434-011-4440-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Lu S, Lu Q, Cao Y, Huang C, Xie J, Wang S. The effects of the guide field on the structures of electron density depletions in collisionless magnetic reconnection. CHINESE SCIENCE BULLETIN-CHINESE 2011. [DOI: 10.1007/s11434-010-4250-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Sun X, Intrator TP, Dorf L, Sears J, Furno I, Lapenta G. Flux rope dynamics: experimental study of bouncing and merging. PHYSICAL REVIEW LETTERS 2010; 105:255001. [PMID: 21231595 DOI: 10.1103/physrevlett.105.255001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Indexed: 05/30/2023]
Abstract
We show experimentally for the first time that two mutually attracting flux ropes may bounce back instead of merging together, leading to a variety of dynamics not expected from a two-dimensional model. Attraction forces due to flux rope currents compete with repulsion from field line bending of in-plane and out-of-plane magnetic fields and elastic plasma compression. Bouncing dynamics occurs if the line-bending force due to an out-of-plane field dominates. Otherwise, the ropes merge. Further reduction in the field line-bending force results in violently erratic magnetic states.
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Affiliation(s)
- X Sun
- Los Alamos National Laboratory, Mail Stop E526, Los Alamos, New Mexico 87545, USA
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16
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Wang R, Lu Q, Du A, Wang S. In situ observations of a secondary magnetic island in an ion diffusion region and associated energetic electrons. PHYSICAL REVIEW LETTERS 2010; 104:175003. [PMID: 20482115 DOI: 10.1103/physrevlett.104.175003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Indexed: 05/29/2023]
Abstract
Numerical simulations have predicted that an extended current sheet may be unstable to secondary magnetic islands in the vicinity of the X line, and these islands can dramatically influence the reconnection rate. In this Letter, we present the first evidence of such a secondary island near the center of an ion diffusion region, which is consistent with the action of the secondary island instability occurring in the vicinity of the X line. The island is squashed in the z direction with a strong core magnetic field. Energetic electrons with anisotropic or field-aligned bidirectional fluxes are found in the ion diffusion region, and the enhancement of energetic electron fluxes is more obvious inside the secondary island.
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Affiliation(s)
- Rongsheng Wang
- CAS Key Laboratory of Basic Plasma Physics, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
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17
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Guo J. Electron dynamics in collisionless magnetic reconnection with a PIC simulation. Sci Bull (Beijing) 2009. [DOI: 10.1007/s11434-008-0438-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Pritchett PL. Collisionless magnetic reconnection in an asymmetric current sheet. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007ja012930] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- P. L. Pritchett
- Department of Physics and Astronomy; University of California; Los Angeles California USA
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19
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Drake JF, Swisdak M, Che H, Shay MA. Electron acceleration from contracting magnetic islands during reconnection. Nature 2006; 443:553-6. [PMID: 17024088 DOI: 10.1038/nature05116] [Citation(s) in RCA: 690] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Accepted: 07/19/2006] [Indexed: 11/08/2022]
Abstract
A long-standing problem in the study of space and astrophysical plasmas is to explain the production of energetic electrons as magnetic fields 'reconnect' and release energy. In the Earth's magnetosphere, electron energies reach hundreds of thousands of electron volts (refs 1-3), whereas the typical electron energies associated with large-scale reconnection-driven flows are just a few electron volts. Recent observations further suggest that these energetic particles are produced in the region where the magnetic field reconnects. In solar flares, upwards of 50 per cent of the energy released can appear as energetic electrons. Here we show that electrons gain kinetic energy by reflecting from the ends of the contracting 'magnetic islands' that form as reconnection proceeds. The mechanism is analogous to the increase of energy of a ball reflecting between two converging walls--the ball gains energy with each bounce. The repetitive interaction of electrons with many islands allows large numbers to be efficiently accelerated to high energy. The back pressure of the energetic electrons throttles reconnection so that the electron energy gain is a large fraction of the released magnetic energy. The resultant energy spectra of electrons take the form of power laws with spectral indices that match the magnetospheric observations.
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Affiliation(s)
- J F Drake
- University of Maryland, College Park, Maryland 20742, USA.
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20
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Zenitani S, Hoshino M. Three-dimensional evolution of a relativistic current sheet: triggering of magnetic reconnection by the guide field. PHYSICAL REVIEW LETTERS 2005; 95:095001. [PMID: 16197219 DOI: 10.1103/physrevlett.95.095001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2005] [Indexed: 05/04/2023]
Abstract
The linear and nonlinear evolution of a relativistic current sheet of pair (e(+/-)) plasmas is investigated by three-dimensional particle-in-cell simulations. In a Harris configuration, it is obtained that the magnetic energy is fast dissipated by the relativistic drift kink instability (RDKI). However, when a current-aligned magnetic field (the so-called "guide field") is introduced, the RDKI is stabilized by the magnetic tension force and it separates into two obliquely propagating modes, which we call the relativistic drift-kink-tearing instability. These two waves deform the current sheet so that they trigger relativistic magnetic reconnection at a crossover thinning point. Since relativistic reconnection produces a lot of nonthermal particles, the guide field is of critical importance to study the energetics of a relativistic current sheet.
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Affiliation(s)
- S Zenitani
- Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan.
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21
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Drake JF, Shay MA, Thongthai W, Swisdak M. Production of energetic electrons during magnetic reconnection. PHYSICAL REVIEW LETTERS 2005; 94:095001. [PMID: 15783970 DOI: 10.1103/physrevlett.94.095001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Indexed: 05/24/2023]
Abstract
The production of energetic electrons during magnetic reconnection is explored with full particle simulations and analytic analysis. Density cavities generated along separatrices bounding growing magnetic islands support parallel electric fields that act as plasma accelerators. Electrons because of their low mass are fast enough to make multiple passes through these acceleration cavities and are therefore capable of reaching relativistic energies.
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Affiliation(s)
- J F Drake
- University of Maryland, College Park, Maryland 20742, USA
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22
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Cattell C. Cluster observations of electron holes in association with magnetotail reconnection and comparison to simulations. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004ja010519] [Citation(s) in RCA: 223] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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