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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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Sun W, Turner DL, Zhang Q, Wang S, Egedal J, Leonard T, Slavin JA, Hu Q, Cohen IJ, Genestreti K, Poh G, Gershman DJ, Smith A, Le G, Nakamura R, Giles BL, Ergun RE, Burch JL. Properties and Acceleration Mechanisms of Electrons Up To 200 keV Associated With a Flux Rope Pair and Reconnection X-Lines Around It in Earth's Plasma Sheet. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2022; 127:e2022JA030721. [PMID: 37032657 PMCID: PMC10078532 DOI: 10.1029/2022ja030721] [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: 06/06/2022] [Revised: 10/26/2022] [Accepted: 12/02/2022] [Indexed: 06/19/2023]
Abstract
The properties and acceleration mechanisms of electrons (<200 keV) associated with a pair of tailward traveling flux ropes and accompanied reconnection X-lines in Earth's plasma sheet are investigated with MMS measurements. Energetic electrons are enhanced on both boundaries and core of the flux ropes. The power-law spectra of energetic electrons near the X-lines and in flux ropes are harder than those on flux rope boundaries. Theoretical calculations show that the highest energy of adiabatic electrons is a few keV around the X-lines, tens of keV immediately downstream of the X-lines, hundreds of keV on the flux rope boundaries, and a few MeV in the flux rope cores. The X-lines cause strong energy dissipation, which may generate the energetic electron beams around them. The enhanced electron parallel temperature can be caused by the curvature-driven Fermi acceleration and the parallel electric potential. Betatron acceleration due to the magnetic field compression is strong on flux rope boundaries, which enhances energetic electrons in the perpendicular direction. Electrons can be trapped between the flux rope pair due to mirror force and parallel electric potential. Electrostatic structures in the flux rope cores correspond to potential drops up to half of the electron temperature. The energetic electrons and the electron distribution functions in the flux rope cores are suggested to be transported from other dawn-dusk directions, which is a 3-dimensional effect. The acceleration and deceleration of the Betatron and Fermi processes appear alternately indicating that the magnetic field and plasma are turbulent around the flux ropes.
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Affiliation(s)
- Weijie Sun
- Department of Climate and Space Sciences and EngineeringUniversity of MichiganAnn ArborMIUSA
| | - Drew L. Turner
- Space Exploration SectorJohns Hopkins Applied Physics LaboratoryLaurelMDUSA
| | - Qile Zhang
- Los Alamos National LaboratoryLos AlamosNMUSA
| | - Shan Wang
- Department of AstronomyUniversity of MarylandCollege ParkMDUSA
| | - Jan Egedal
- Department of PhysicsUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Trevor Leonard
- Laboratory for Atmospheric and Space PhysicsUniversity of Colorado BoulderBoulderCOUSA
| | - James A. Slavin
- Department of Climate and Space Sciences and EngineeringUniversity of MichiganAnn ArborMIUSA
| | - Qiang Hu
- Department of Space ScienceCenter for Space Plasma and Aeronomic ResearchThe University of Alabama in HuntsvilleHuntsvilleALUSA
| | - Ian J. Cohen
- Space Exploration SectorJohns Hopkins Applied Physics LaboratoryLaurelMDUSA
| | | | - Gangkai Poh
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- Center for Research and Exploration in Space Sciences and Technology IICatholic University of AmericaWashingtonDCUSA
| | | | - Andrew Smith
- Mullard Space Science LaboratoryUniversity College LondonSurreyUK
- Department of Mathematics, Physics and Electrical EngineeringNorthumbria UniversityNewcastle Upon TyneUK
| | - Guan Le
- NASA Goddard Space Flight CenterGreenbeltMDUSA
| | - Rumi Nakamura
- Space Research InstituteAustrian Academy of SciencesGrazAustria
| | | | - Robert E. Ergun
- Department of Astrophysical and Planetary SciencesUniversity of Colorado BoulderBoulderCOUSA
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Direct evidence of secondary reconnection inside filamentary currents of magnetic flux ropes during magnetic reconnection. Nat Commun 2020; 11:3964. [PMID: 32769991 PMCID: PMC7415135 DOI: 10.1038/s41467-020-17803-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 07/09/2020] [Indexed: 11/16/2022] Open
Abstract
Magnetic reconnection is a fundamental plasma process, by which magnetic energy is explosively released in the current sheet to energize charged particles and to create bi-directional Alfvénic plasma jets. Numerical simulations predicted that evolution of the reconnecting current sheet is dominated by formation and interaction of magnetic flux ropes, which finally leads to turbulence. Accordingly, most volume of the reconnecting current sheet is occupied by the ropes, and energy dissipation occurs via multiple relevant mechanisms, e.g., the parallel electric field, the rope coalescence and the rope contraction. As an essential element of the reconnecting current sheet, however, how these ropes evolve has been elusive. Here, we present direct evidence of secondary reconnection in the filamentary currents within the ropes. The observations indicate that secondary reconnection can make a significant contribution to energy conversion in the kinetic scale during turbulent reconnection. Magnetic reconnection is a fundamental plasma process of magnetic energy conversion to kinetic energy. Here, the authors show direct evidence of secondary reconnection in the filamentary currents within the flux ropes indicating a significant contribution to energy conversion in the kinetic scale during turbulent reconnection.
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Guo R, Pu Z, Fu S, Xie L, Dunlop M, Bogdanova YV, He J, Wang X, Yao Z. Evolution of clustered magnetic nulls in a turbulent-like reconnection region in the magnetotail. Sci Bull (Beijing) 2016. [DOI: 10.1007/s11434-016-1121-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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A review of recent studies on coronal dynamics: Streamers, coronal mass ejections, and their interactions. CHINESE SCIENCE BULLETIN-CHINESE 2013. [DOI: 10.1007/s11434-013-5669-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Dong QL, Wang SJ, Lu QM, Huang C, Yuan DW, Liu X, Lin XX, Li YT, Wei HG, Zhong JY, Shi JR, Jiang SE, Ding YK, Jiang BB, Du K, He XT, Yu MY, Liu CS, Wang S, Tang YJ, Zhu JQ, Zhao G, Sheng ZM, Zhang J. Plasmoid ejection and secondary current sheet generation from magnetic reconnection in laser-plasma interaction. PHYSICAL REVIEW LETTERS 2012; 108:215001. [PMID: 23003270 DOI: 10.1103/physrevlett.108.215001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Indexed: 06/01/2023]
Abstract
Reconnection of the self-generated magnetic fields in laser-plasma interaction was first investigated experimentally by Nilson et al. [Phys. Rev. Lett. 97, 255001 (2006)] by shining two laser pulses a distance apart on a solid target layer. An elongated current sheet (CS) was observed in the plasma between the two laser spots. In order to more closely model magnetotail reconnection, here two side-by-side thin target layers, instead of a single one, are used. It is found that at one end of the elongated CS a fanlike electron outflow region including three well-collimated electron jets appears. The (>1 MeV) tail of the jet energy distribution exhibits a power-law scaling. The enhanced electron acceleration is attributed to the intense inductive electric field in the narrow electron dominated reconnection region, as well as additional acceleration as they are trapped inside the rapidly moving plasmoid formed in and ejected from the CS. The ejection also induces a secondary CS.
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Affiliation(s)
- Quan-Li Dong
- Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China.
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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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Wang Y, Wei FS, Feng XS, Zhang SH, Zuo PB, Sun TR. Energetic electrons associated with magnetic reconnection in the magnetic cloud boundary layer. PHYSICAL REVIEW LETTERS 2010; 105:195007. [PMID: 21231178 DOI: 10.1103/physrevlett.105.195007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Indexed: 05/30/2023]
Abstract
Here is reported in situ observation of energetic electrons (∼100-500 keV) associated with magnetic reconnection in the solar wind by the ACE and Wind spacecraft. The properties of this magnetic cloud driving reconnection and the associated energetic electron acceleration problem are discussed. Further analyses indicate that the electric field acceleration and Fermi-type mechanism are two fundamental elements in the electron acceleration processes and the trapping effect of the specific magnetic field configuration maintains the acceleration status that increases the totally gained energy.
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Affiliation(s)
- Y Wang
- SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Science, Beijing 100049, China
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