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Manzini D, Sahraoui F, Califano F. Subion-Scale Turbulence Driven by Magnetic Reconnection. PHYSICAL REVIEW LETTERS 2023; 130:205201. [PMID: 37267550 DOI: 10.1103/physrevlett.130.205201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 02/11/2023] [Accepted: 04/07/2023] [Indexed: 06/04/2023]
Abstract
The interplay between plasma turbulence and magnetic reconnection remains an unsettled question in astrophysical and laboratory plasmas. Here, we report the first observational evidence that magnetic reconnection drives subion-scale turbulence in magnetospheric plasmas by transferring energy to small scales. We employ a spatial "coarse-grained" model of Hall magnetohydrodynamics, enabling us to measure the nonlinear energy transfer rate across scale ℓ at position x. Its application to Magnetospheric Multiscale mission data shows that magnetic reconnection drives intense energy transfer to subion-scales. This observational evidence is remarkably supported by the results from Hybrid Vlasov-Maxwell simulations of turbulence to which the coarse-grained model is also applied. These results can potentially answer some open questions on plasma turbulence in planetary environments.
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Affiliation(s)
- D Manzini
- Laboratoire de Physique des Plasmas (LPP), CNRS, École Polytechnique, Sorbonne Université, Université Paris-Saclay, Observatoire de Paris, 91120 Palaiseau, France
- Dipartimento di Fisica "Enrico Fermi," Università di Pisa, Pisa 56127, Italy
| | - F Sahraoui
- Laboratoire de Physique des Plasmas (LPP), CNRS, École Polytechnique, Sorbonne Université, Université Paris-Saclay, Observatoire de Paris, 91120 Palaiseau, France
| | - F Califano
- Dipartimento di Fisica "Enrico Fermi," Università di Pisa, Pisa 56127, Italy
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2
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George DE, Jahn J. Energized Oxygen in the Magnetotail: Onset and Evolution of Magnetic Reconnection. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2022; 127:e2020JA028381. [PMID: 36582491 PMCID: PMC9786576 DOI: 10.1029/2020ja028381] [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: 06/19/2020] [Revised: 08/12/2022] [Accepted: 09/08/2022] [Indexed: 06/17/2023]
Abstract
Oxygen ions are a major constituent of magnetospheric plasma, yet the role of oxygen in processes such as magnetic reconnection continues to be poorly understood. Observations show that significant amounts of energized O+ can be present in a magnetotail current sheet (CS). A population of thermal O+ only has a relatively minor effect on magnetic reconnection. Despite this, published studies have so far only concentrated on the role of the low-energy thermal O+. We present a study of magnetic reconnection in a thinning CS with energized O+ present. Well-established, three-species, 2.5D particle-in-cell (PIC) kinetic simulations are used. Simulations of thermal H+ and thermal O+ validate our setup against published results. We then energize a thermal background O+ based on published in situ measurements. A range of energization is applied to the background O+. We discuss the effects of energized O+ on CS thinning and the onset and evolution of magnetic reconnection. The presence of energized O+ causes a two-regime onset response in a thinning CS. As energization increases in the lower-regime, reconnection develops at a single primary X-line, increases time-to-onset, and suppresses the rate of evolution. As energization continues to increase in the higher-regime, reconnection develops at multiple X-lines, forming a stochastic plasmoid chain; decreases time-to-onset; and enhances evolution via a plasmoid instability. Energized O+ drives a depletion of the background H+ around the central CS. As the energization increases, the CS thinning begins to slow and eventually reverses.
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Affiliation(s)
- Don E George
- Space Science and EngineeringSouthwest Research InstituteSan AntonioTXUSA
- Department of Physics and AstronomyUniversity of Texas at San AntonioSan AntonioTXUSA
| | - Jörg‐Micha Jahn
- Space Science and EngineeringSouthwest Research InstituteSan AntonioTXUSA
- Department of Physics and AstronomyUniversity of Texas at San AntonioSan AntonioTXUSA
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3
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Sakai K, Moritaka T, Morita T, Tomita K, Minami T, Nishimoto T, Egashira S, Ota M, Sakawa Y, Ozaki N, Kodama R, Kojima T, Takezaki T, Yamazaki R, Tanaka SJ, Aihara K, Koenig M, Albertazzi B, Mabey P, Woolsey N, Matsukiyo S, Takabe H, Hoshino M, Kuramitsu Y. Direct observations of pure electron outflow in magnetic reconnection. Sci Rep 2022; 12:10921. [PMID: 35773286 PMCID: PMC9247195 DOI: 10.1038/s41598-022-14582-3] [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: 02/04/2022] [Accepted: 06/09/2022] [Indexed: 11/25/2022] Open
Abstract
Magnetic reconnection is a universal process in space, astrophysical, and laboratory plasmas. It alters magnetic field topology and results in energy release to the plasma. Here we report the experimental results of a pure electron outflow in magnetic reconnection, which is not accompanied with ion flows. By controlling an applied magnetic field in a laser produced plasma, we have constructed an experiment that magnetizes the electrons but not the ions. This allows us to isolate the electron dynamics from the ions. Collective Thomson scattering measurements reveal the electron Alfvénic outflow without ion outflow. The resultant plasmoid and whistler waves are observed with the magnetic induction probe measurements. We observe the unique features of electron-scale magnetic reconnection simultaneously in laser produced plasmas, including global structures, local plasma parameters, magnetic field, and waves.
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Affiliation(s)
- K Sakai
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan. .,Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - T Moritaka
- Department of Helical Plasma Research, National Institute for Fusion Science, Toki, 509-5292, Japan
| | - T Morita
- Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka, 816-8580, Japan
| | - K Tomita
- Division of Quantum Science and Engineering, Graduate School of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido, 060-8628, Japan
| | - T Minami
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - T Nishimoto
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - S Egashira
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - M Ota
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Y Sakawa
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - N Ozaki
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - R Kodama
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - T Kojima
- Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka, 816-8580, Japan
| | - T Takezaki
- Faculty of Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama, 930-8555, Japan
| | - R Yamazaki
- Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Physical Sciences, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa, 252-5258, Japan
| | - S J Tanaka
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Physical Sciences, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa, 252-5258, Japan
| | - K Aihara
- Department of Physical Sciences, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa, 252-5258, Japan
| | - M Koenig
- LULI-CNRS, CEA, Sorbonne Universités, École Polytechnique, Institut Polytechnique de Paris, F-91120, Palaiseau cedex, France
| | - B Albertazzi
- LULI-CNRS, CEA, Sorbonne Universités, École Polytechnique, Institut Polytechnique de Paris, F-91120, Palaiseau cedex, France
| | - P Mabey
- LULI-CNRS, CEA, Sorbonne Universités, École Polytechnique, Institut Polytechnique de Paris, F-91120, Palaiseau cedex, France
| | - N Woolsey
- Department of Physics, York Plasma Institute, University of York, York, YO10 5DD, UK
| | - S Matsukiyo
- Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka, 816-8580, Japan
| | - H Takabe
- Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei, 10617, Taiwan
| | - M Hoshino
- Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan
| | - Y Kuramitsu
- Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
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4
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Properties of Hall-MHD Turbulence at Sub-Ion Scales: Spectral Transfer Analysis. ATMOSPHERE 2021. [DOI: 10.3390/atmos12121632] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We present results of a multiscale study of Hall-magnetohydrodynamic (MHD) turbulence, carried out on a dataset of compressible nonlinear 2D Hall-MHD numerical simulations of decaying Alfvénic turbulence. For the first time, we identify two distinct regimes of fully developed turbulence. In the first one, the power spectrum of the turbulent magnetic fluctuations at sub-ion scales exhibits a power law with a slope of ∼−2.9, typically observed both in solar wind and in magnetosheath turbulence. The second regime, instead, shows a slope of −7/3, in agreement with classical theoretical models of Hall-MHD turbulence. A spectral-transfer analysis reveals that the latter regime occurs when the energy transfer rate at sub-ion scales is dominated by the Hall term, whereas in the former regime, the governing process is the dissipation (and the system exhibits large intermittency). Results of this work are relevant to the space plasma community, as they may potentially reconcile predictions from theoretical models with results from numerical simulations and spacecraft observations.
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5
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Jafari A, Vishniac E, Vaikundaraman V. Statistical analysis of stochastic magnetic fields. Phys Rev E 2020; 101:022122. [PMID: 32168717 DOI: 10.1103/physreve.101.022122] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 01/28/2020] [Indexed: 11/07/2022]
Abstract
Previous work has introduced scale-split energy density ψ_{l,L}(x,t)=1/2B_{l}·B_{L} for vector field B(x,t) coarse grained at scales l and L, in order to quantify the field stochasticity or spatial complexity. In this formalism, the L_{p} norms S_{p}(t)=1/2||1-B[over ̂]_{l}·B[over ̂]_{L}||_{p}, pth-order stochasticity level, and E_{p}(t)=1/2||B_{l}B_{L}||_{p}, pth order mean cross energy density, are used to analyze the evolution of the stochastic field B(x,t). Application to turbulent magnetic fields leads to the prediction that turbulence in general tends to tangle an initially smooth magnetic field increasing the magnetic stochasticity level, ∂_{t}S_{p}>0. An increasing magnetic stochasticity in turn leads to disalignments of the coarse-grained fields B_{d} at smaller scales, d≪L, thus they average to weaker fields B_{L} at larger scales upon coarse graining, i.e., ∂_{t}E_{p}<0. Magnetic field resists the tangling effect of the turbulence by means of magnetic tension force. This can lead at some point to a sudden slippage between the field and fluid, decreasing the stochasticity ∂_{t}S_{p}<0 and increasing the energy ∂_{t}E_{p}>0 by aligning small-scale fields B_{d}. Thus the maxima (minima) of magnetic stochasticity are expected to approximately coincide with the minima (maxima) of cross energy density, occurrence of which corresponds to slippage of the magnetic field through the fluid. In this formalism, magnetic reconnection and field-fluid slippage both correspond to T_{p}=∂_{t}S_{p}=0and∂_{t}T_{2}<0. Previous work has also linked field-fluid slippage to magnetic reconnection invoking totally different approaches. In this paper, (a) we test these theoretical predictions numerically using a homogeneous, incompressible magnetohydrodynamic (MHD) simulation. Apart from expected small-scale deviations, possibly due to, e.g., intermittency and strong field annihilation, the theoretically predicted global relationship between stochasticity and cross energy is observed in different subvolumes of the simulation box. This indicate ubiquitous local field-fluid slippage and reconnection events in MHD turbulence. In addition, (b) we show that the conditions T_{p}=∂_{t}S_{p}=0and∂_{t}T_{p}<0 lead to sudden increases in kinetic stochasticity level, i.e., τ_{p}=∂_{t}s_{p}(t)>0 with s_{p}(t)=1/2||1-u[over ̂]_{l}.u[over ̂]_{L}||_{p}, which may correspond to fluid jets spontaneously driven by sudden field-fluid slippage-magnetic reconnection. Otherwise, they may correspond only to field-fluid slippage without energy dissipation. This picture, therefore, suggests defining reconnection as field-fluid slippage (changes in S_{p}) accompanied with magnetic energy dissipation (changes in E_{p}). All in all, these provide a statistical approach to the reconnection in terms of the time evolution of magnetic and kinetic stochasticities, S_{p} and s_{p}, their time derivatives, T_{p}=∂_{t}S_{p}, τ_{p}=∂_{t}s_{p}, and corresponding cross energies, E_{p}, e_{p}(t)=1/2||u_{l}u_{L}||_{p}. Furthermore, (c) we introduce the scale-split magnetic helicity based on which we discuss the energy or stochasticity relaxation of turbulent magnetic fields-a generalized Taylor relaxation. Finally, (d) we construct and numerically test a toy model, which resembles a classical version of quantum mean field Ising model for magnetized fluids, in order to illustrate how turbulent energy can affect magnetic stochasticity in the weak field regime.
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Affiliation(s)
- Amir Jafari
- Department of Physics & Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Ethan Vishniac
- Department of Physics & Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
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6
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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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7
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Kawazura Y. Modification of magnetohydrodynamic waves by the relativistic Hall effect. Phys Rev E 2017; 96:013207. [PMID: 29347158 DOI: 10.1103/physreve.96.013207] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Indexed: 11/07/2022]
Abstract
This study shows that a relativistic Hall effect significantly changes the properties of wave propagation by deriving a linear dispersion relation for relativistic Hall magnetohydrodynamics (HMHD). Whereas, in nonrelativistic HMHD, the phase and group velocities of fast magnetosonic wave become anisotropic with an increasing Hall effect, the relativistic Hall effect brings upper bounds to the anisotropies. The Alfvén wave group velocity with strong Hall effect also becomes less anisotropic than the nonrelativistic case. Moreover, the group velocity surfaces of Alfvén and fast waves coalesce into a single surface in the direction other than near perpendicular to the ambient magnetic field. It is also remarkable that a characteristic scale length of the relativistic HMHD depends on ion temperature, magnetic field strength, and density while the nonrelativistic HMHD scale length, i.e., ion skin depth, depends only on density. The modified characteristic scale length increases as the ion temperature increases and decreases as the magnetic field strength increases.
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Affiliation(s)
- Yohei Kawazura
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3NP, United Kingdom
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8
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Waelbroeck FL. Models for Sub-Alfvénic Magnetodynamics of Fusion Plasmas. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst11-a11692] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- F. L. Waelbroeck
- Institute for Fusion Studies, University of Texas, Austin, Texas 78712
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9
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Zweibel EG, Yamada M. Perspectives on magnetic reconnection. Proc Math Phys Eng Sci 2016; 472:20160479. [PMID: 28119547 PMCID: PMC5247523 DOI: 10.1098/rspa.2016.0479] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 10/31/2016] [Indexed: 11/12/2022] Open
Abstract
Magnetic reconnection is a topological rearrangement of magnetic field that occurs on time scales much faster than the global magnetic diffusion time. Since the field lines break on microscopic scales but energy is stored and the field is driven on macroscopic scales, reconnection is an inherently multi-scale process that often involves both magnetohydrodynamic (MHD) and kinetic phenomena. In this article, we begin with the MHD point of view and then describe the dynamics and energetics of reconnection using a two-fluid formulation. We also focus on the respective roles of global and local processes and how they are coupled. We conclude that the triggers for reconnection are mostly global, that the key energy conversion and dissipation processes are either local or global, and that the presence of a continuum of scales coupled from microscopic to macroscopic may be the most likely path to fast reconnection.
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Affiliation(s)
- Ellen G Zweibel
- Departments of Astronomy and Physics, University of Wisconsin-Madison, Madison, WI, USA; Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ, USA
| | - Masaaki Yamada
- Departments of Astronomy and Physics, University of Wisconsin-Madison, Madison, WI, USA; Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ, USA
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10
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Stanier A, Daughton W, Chacón L, Karimabadi H, Ng J, Huang YM, Hakim A, Bhattacharjee A. Role of Ion Kinetic Physics in the Interaction of Magnetic Flux Ropes. PHYSICAL REVIEW LETTERS 2015; 115:175004. [PMID: 26551121 DOI: 10.1103/physrevlett.115.175004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Indexed: 06/05/2023]
Abstract
To explain many natural magnetized plasma phenomena, it is crucial to understand how rates of collisionless magnetic reconnection scale in large magnetohydrodynamic (MHD) scale systems. Simulations of isolated current sheets conclude such rates are independent of system size and can be reproduced by the Hall-MHD model, but neglect sheet formation and coupling to MHD scales. Here, it is shown for the problem of flux-rope merging, which includes this formation and coupling, that the Hall-MHD model fails to reproduce the kinetic results. The minimum sufficient model must retain ion kinetic effects, which set the ion diffusion region geometry and give time-averaged rates that reduce significantly with system size, leading to different global evolution in large systems.
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Affiliation(s)
- A Stanier
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - W Daughton
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - L Chacón
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - H Karimabadi
- SciberQuest, Inc., Del Mar, California 92014, USA
| | - J Ng
- Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - Y-M Huang
- Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - A Hakim
- Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - A Bhattacharjee
- Center for Heliophysics, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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11
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Matthaeus WH, Wan M, Servidio S, Greco A, Osman KT, Oughton S, Dmitruk P. Intermittency, nonlinear dynamics and dissipation in the solar wind and astrophysical plasmas. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:20140154. [PMID: 25848085 PMCID: PMC4394684 DOI: 10.1098/rsta.2014.0154] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/12/2015] [Indexed: 05/29/2023]
Abstract
An overview is given of important properties of spatial and temporal intermittency, including evidence of its appearance in fluids, magnetofluids and plasmas, and its implications for understanding of heliospheric plasmas. Spatial intermittency is generally associated with formation of sharp gradients and coherent structures. The basic physics of structure generation is ideal, but when dissipation is present it is usually concentrated in regions of strong gradients. This essential feature of spatial intermittency in fluids has been shown recently to carry over to the realm of kinetic plasma, where the dissipation function is not known from first principles. Spatial structures produced in intermittent plasma influence dissipation, heating, and transport and acceleration of charged particles. Temporal intermittency can give rise to very long time correlations or a delayed approach to steady-state conditions, and has been associated with inverse cascade or quasi-inverse cascade systems, with possible implications for heliospheric prediction.
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Affiliation(s)
- W H Matthaeus
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA Dipartimento di Fisica, Università della Calabria, Arcavacata, Rende, Italy Dipartimento di Fisica e Astronomia, Università di Firenze, Firenze, Italy
| | - Minping Wan
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
| | - S Servidio
- Dipartimento di Fisica, Università della Calabria, Arcavacata, Rende, Italy
| | - A Greco
- Dipartimento di Fisica, Università della Calabria, Arcavacata, Rende, Italy
| | - K T Osman
- Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL, UK
| | - S Oughton
- Department of Mathematics, University of Waikato, Hamilton, New Zealand
| | - P Dmitruk
- Departamento de Fisica, FCEN, Universidad de Buenos Aires, Buenos Aires, Argentina
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12
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Martin LN, De Vita G, Sorriso-Valvo L, Dmitruk P, Nigro G, Primavera L, Carbone V. Cancellation properties in Hall magnetohydrodynamics with a strong guide magnetic field. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:063107. [PMID: 24483577 DOI: 10.1103/physreve.88.063107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 11/15/2013] [Indexed: 06/03/2023]
Abstract
We present a signed measure analysis of compressible Hall magnetohydrodynamic turbulence with an external guide field. Signed measure analysis allows us to characterize the scaling behavior of the sign-oscillating flow structures and their geometrical properties (fractal dimensions of structures). A reduced numerical model, valid when a strong guide magnetic field is present, is used here. In order to discuss the effect of the Hall term, different values for the ion skin depth are considered in the simulations. Results show that as the Hall term is increased, the fractal dimension of the current and vorticity sheets decreases. This observation, together with previous analysis of the same fields, provides a comprehensive description of the effect of the Hall force on the formation of structures. Two main processes are identified, namely, the widening and unraveling of the sheets.
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Affiliation(s)
- L N Martin
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, Buenos Aires 1428, Argentina
| | - G De Vita
- Dipartimento di Fisica, Università degli Studi della Calabria, 87036 Rende, Cosenza, Italy
| | - L Sorriso-Valvo
- CNR, IPCF, UOS di Cosenza, 87036 Rende, Cosenza, Italy and Space Sciences Laboratory, University of California, Berkeley, Berkeley, California 94720, USA
| | - P Dmitruk
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and IFIBA, CONICET, Buenos Aires 1428, Argentina
| | - G Nigro
- Dipartimento di Fisica, Università degli Studi della Calabria, 87036 Rende, Cosenza, Italy
| | - L Primavera
- Dipartimento di Fisica, Università degli Studi della Calabria, 87036 Rende, Cosenza, Italy
| | - V Carbone
- Dipartimento di Fisica, Università degli Studi della Calabria, 87036 Rende, Cosenza, Italy
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13
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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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14
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Chai L, Li Y, Wang S, Shen C. Low-frequency waves in magnetic reconnection. CHINESE SCIENCE BULLETIN-CHINESE 2012. [DOI: 10.1007/s11434-011-4910-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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15
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Wang X, Xiao C, Pu Z, Wang J. Recent progresses in theoretical studies and satellite observations for collisionless magnetic reconnection. CHINESE SCIENCE BULLETIN-CHINESE 2012. [DOI: 10.1007/s11434-012-5045-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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16
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Singh N. Whistler mode based explanation for the fast reconnection rate measured in the mit versatile toroidal facility. PHYSICAL REVIEW LETTERS 2011; 107:245003. [PMID: 22243006 DOI: 10.1103/physrevlett.107.245003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Indexed: 05/31/2023]
Abstract
Despite the widely discussed role of whistler waves in mediating magnetic reconnection (MR), the direct connection between such waves and the MR has not been demonstrated by comparing the characteristic temporal and spatial features of the waves and the MR process. Using the whistler wave dispersion relation, we theoretically predict the experimentally measured rise time (τ(rise)) of a few microseconds for the fast rising MR rate in the Versatile Toroidal Facility at MIT. The rise time is closely given by the inverse of the frequency bandwidth of the whistler waves generated in the evolving current sheet. The wave frequencies lie much above the ion cyclotron frequency, but they are limited to less than 0.1% of the electron cyclotron frequency in the argon plasma. The maximum normalized MR rate R=0.35 measured experimentally is precisely predicted by the angular dispersion of the whistler waves.
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Affiliation(s)
- Nagendra Singh
- Electrical and Computer Engineering, University of Alabama, Huntsville, Alabama 35899, USA
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17
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Aunai N, Belmont G, Smets R. Proton acceleration in antiparallel collisionless magnetic reconnection: Kinetic mechanisms behind the fluid dynamics. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011ja016688] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- N. Aunai
- Laboratoire de Physique des Plasmas, Ecole Polytechnique; Palaiseau France
| | - G. Belmont
- Laboratoire de Physique des Plasmas, Ecole Polytechnique; Palaiseau France
| | - R. Smets
- Laboratoire de Physique des Plasmas, Ecole Polytechnique; Palaiseau France
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18
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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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19
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Daughton W, Roytershteyn V, Albright BJ, Karimabadi H, Yin L, Bowers KJ. Transition from collisional to kinetic regimes in large-scale reconnection layers. PHYSICAL REVIEW LETTERS 2009; 103:065004. [PMID: 19792577 DOI: 10.1103/physrevlett.103.065004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Indexed: 05/28/2023]
Abstract
Using fully kinetic simulations with a Fokker-Planck collision operator, it is demonstrated that Sweet-Parker reconnection layers are unstable to plasmoids (secondary islands) for Lundquist numbers beyond S greater, similar 1000. The instability is increasingly violent at higher Lundquist numbers, both in terms of the number of plasmoids produced and the super-Alfvénic growth rate. A dramatic enhancement in the reconnection rate is observed when the half-thickness of the current sheet between two plasmoids approaches the ion inertial length. During this transition to kinetic scales, the reconnection electric field rapidly exceeds the runaway limit, resulting in the formation of electron-scale current layers that are unstable to the continual formation of new plasmoids.
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Affiliation(s)
- W Daughton
- Los Alamos National Laboratory, Los Alamos, New Mexico 87544, USA
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20
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Nakamura TKM, Fujimoto M. Magnetic effects on the coalescence of Kelvin-Helmholtz vortices. PHYSICAL REVIEW LETTERS 2008; 101:165002. [PMID: 18999678 DOI: 10.1103/physrevlett.101.165002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2008] [Indexed: 05/27/2023]
Abstract
We simulate the coalescence process of MHD-scale Kelvin-Helmholtz vortices with the electron inertial effects taken into account. Reconnection of highly stretched magnetic field lines within a rolled-up vortex destroys the vortex itself and the coalescence process, which is well known in ordinary fluid dynamics, is seen to be inhibited. When the magnetic field is initially antiparallel across the shear layer, on the other hand, multiple vortices are seen to coalesce continuously because another type of magnetic reconnection prevents the vortex decay. This type of reconnection at the hyperbolic point also changes the field line connectivity and thus leads to large-scale plasma mixing across the shear layer.
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Affiliation(s)
- T K M Nakamura
- Japan Aerospace Exploration Agency/Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa, Japan.
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21
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Ren Y, Yamada M, Ji H, Gerhardt SP, Kulsrud R. Identification of the electron-diffusion region during magnetic reconnection in a laboratory plasma. PHYSICAL REVIEW LETTERS 2008; 101:085003. [PMID: 18764626 DOI: 10.1103/physrevlett.101.085003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Indexed: 05/26/2023]
Abstract
We report the first identification of the electron-diffusion region, where demagnetized electrons are accelerated to super-Alfvénic speed, in a reconnecting laboratory plasma. The width of the electron-diffusion region scales with the electron skin depth [ approximately (5.5-7.5)c/omega_{pe}] and the peak electron outflow velocity scales with the electron Alfvén velocity [ approximately (0.12-0.16)V_{eA}], independent of ion mass.
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Affiliation(s)
- Yang Ren
- Center for Magnetic Self-organization in Laboratory and Astrophysical Plasmas, Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
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22
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Núñez M. A theorem of existence for the equations of magnetohydrodynamics of partially ionized plasmas. Proc Math Phys Eng Sci 2008. [DOI: 10.1098/rspa.2007.0259] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The equations of magnetohydrodynamics of partially ionized plasmas have been known for a long time, but rarely studied. Instead, several simplifications have been applied to different physical models, ranging from magnetic reconnection to ambipolar drift. The original system relates the electric field to kinetic magnitudes by means of a non-local law, so that the equations describing it involve partial differentials as well as functional operators. We prove a theorem of existence and uniqueness of solutions for a finite time by means of a fixed point argument in an appropriate functional setting.
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Affiliation(s)
- Manuel Núñez
- Departamento de Análisis Matemático, Universidad de Valladolid47005 Valladolid, Spain
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23
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Materassi M, Consolini G. Magnetic reconnection rate in space plasmas: a fractal approach. PHYSICAL REVIEW LETTERS 2007; 99:175002. [PMID: 17995340 DOI: 10.1103/physrevlett.99.175002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Indexed: 05/25/2023]
Abstract
Magnetic reconnection is generally discussed via a fluid description. Here, we evaluate the reconnection rate assuming a fractal topology of the reconnection region. The central idea is that the fluid hypothesis may be violated at the scales where reconnection takes place. The reconnection rate, expressed as the Alfvén Mach number of the plasma moving toward the diffusion region, is shown to depend on the fractal dimension and on the sizes of the reconnection or diffusion region. This mechanism is more efficient than prediction of the Sweet-Parker model and even Petschek's model for finite magnetic Reynolds number. A good agreement also with rates given by Hall MHD models is found. A discussion of the fractal assumption on the diffusion region in terms of current microstructures is proposed. The comparison with in-situ satellite observations suggests the reconnection region to be a filamentary domain.
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Affiliation(s)
- Massimo Materassi
- Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, V. Madonna del Piano 10, I-50019 Sesto Fiorentino, Italy. massimo.materassi@fi..isc.cnr.it
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24
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Abstract
We present a theory of transport of magnetic flux and momentum in two fluid three-dimensional reduced magnetohydrodynamic (MHD) turbulence. By including the effects of shear flows and magnetic fields consistently, we show that kinetic Alfven waves can help weaken the quenching in turbulent transport of a strong magnetic field B0 found in single fluid MHD turbulence, leading to turbulent magnetic diffusivity eta(T) proportional (eta/Omega)(1/3)B(0)(-2). Here, eta and Omega are the Ohmic diffusivity and the shearing rate of the shear flow. Momentum transport is diffusive, with the value of eddy viscosity larger than that in single fluid MHD turbulence. The effects of drift waves are found to be weaker. Implications for the instability of shear flows are discussed.
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Affiliation(s)
- Eun-jin Kim
- Department of Applied Mathematics, University of Sheffield, Sheffield, S3 7RH, United Kingdom
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25
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Shay MA, Drake JF, Swisdak M. Two-scale structure of the electron dissipation region during collisionless magnetic reconnection. PHYSICAL REVIEW LETTERS 2007; 99:155002. [PMID: 17995175 DOI: 10.1103/physrevlett.99.155002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Indexed: 05/25/2023]
Abstract
Particle-in-cell simulations of collisionless magnetic reconnection are presented that demonstrate that reconnection remains fast in very large systems. The electron dissipation region develops a distinct two-scale structure along the outflow direction. Consistent with fast reconnection, the length of the electron current layer stabilizes and decreases with decreasing electron mass, approaching the ion inertial length for a proton-electron plasma. Surprisingly, the electrons form a super-Alfvénic outflow jet that remains decoupled from the magnetic field and extends large distances downstream from the x line.
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Affiliation(s)
- M A Shay
- Department of Physics & Astronomy, 217 Sharp Lab, University of Delaware, Newark, Delaware 19716, USA.
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26
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27
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Khotyaintsev YV, Vaivads A, Retinò A, André M, Owen CJ, Nilsson H. Formation of inner structure of a reconnection separatrix region. PHYSICAL REVIEW LETTERS 2006; 97:205003. [PMID: 17155688 DOI: 10.1103/physrevlett.97.205003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Indexed: 05/12/2023]
Abstract
We present multipoint spacecraft observations at the dayside magnetopause of a magnetic reconnection separatrix region. This region separates two plasmas with significantly different temperatures and densities, at a large distance from the X line. We identify which terms in the generalized Ohm's law balance the observed electric field throughout the separatrix region. The electric field inside a thin approximately c/omega pi Hall layer is balanced by the j x B/ne term while other terms dominate elsewhere. On the low density side of the region we observe a density cavity which forms due to the escape of magnetospheric electrons along the newly opened field lines. The perpendicular electric field inside the cavity constitutes a potential jump of several kV. The observed potential jump and field aligned currents can be responsible for strong aurora.
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Affiliation(s)
- Yu V Khotyaintsev
- Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden
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28
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Inomoto M, Gerhardt SP, Yamada M, Ji H, Belova E, Kuritsyn A, Ren Y. Coupling between global geometry and the local hall effect leading to reconnection-layer symmetry breaking. PHYSICAL REVIEW LETTERS 2006; 97:135002. [PMID: 17026040 DOI: 10.1103/physrevlett.97.135002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Indexed: 05/12/2023]
Abstract
The coupling between the global reconnection geometry and the local microphysics, caused by the Hall effect, is studied during counterhelicity plasma merging in the magnetic reconnection experiment. The structure of the reconnection layer is significantly modified by reversing the sign of the toroidal fields, which affects the manifestation of the Hall effect in the collisionless regime. The local two-fluids physics changes the global boundary conditions, and this combination effect consequently provides different reconnection rates, magnetic field structure, and plasma flow patterns for two different counterhelicity merging cases in the collisionless regime.
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Affiliation(s)
- Michiaki Inomoto
- Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543, USA
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29
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Wygant JR, Cattell CA, Lysak R, Song Y, Dombeck J, McFadden J, Mozer FS, Carlson CW, Parks G, Lucek EA, Balogh A, Andre M, Reme H, Hesse M, Mouikis C. Cluster observations of an intense normal component of the electric field at a thin reconnecting current sheet in the tail and its role in the shock-like acceleration of the ion fluid into the separatrix region. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2004ja010708] [Citation(s) in RCA: 227] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- J. R. Wygant
- School of Physics and Astronomy; University of Minnesota; Minneapolis Minnesota USA
| | - C. A. Cattell
- School of Physics and Astronomy; University of Minnesota; Minneapolis Minnesota USA
| | - R. Lysak
- School of Physics and Astronomy; University of Minnesota; Minneapolis Minnesota USA
| | - Y. Song
- School of Physics and Astronomy; University of Minnesota; Minneapolis Minnesota USA
| | - J. Dombeck
- School of Physics and Astronomy; University of Minnesota; Minneapolis Minnesota USA
| | - J. McFadden
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - F. S. Mozer
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - C. W. Carlson
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - G. Parks
- Space Sciences Laboratory; University of California; Berkeley California USA
| | - E. A. Lucek
- Blackett Laboratory; Imperial College; London UK
| | - A. Balogh
- Blackett Laboratory; Imperial College; London UK
| | - M. Andre
- Swedish Institute of Space Physics; Uppsala Division; Uppsala Sweden
| | - H. Reme
- Centre d'Etude Spatiale des Rayonnements; Toulouse France
| | - M. Hesse
- NASA Goddard Space Flight Center; Greenbelt Maryland USA
| | - C. Mouikis
- University of New Hampshire; Durham New Hampshire USA
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30
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Ishizawa A, Horiuchi R. Suppression of Hall-term effects by gyroviscous cancellation in steady collisionless magnetic reconnection. PHYSICAL REVIEW LETTERS 2005; 95:045003. [PMID: 16090817 DOI: 10.1103/physrevlett.95.045003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2005] [Indexed: 05/03/2023]
Abstract
The formation of an ion-dissipation region, in which motions of electrons and ions decouple and fast magnetic reconnection occurs, is demonstrated during a steady state of two-dimensional collisionless driven reconnection by means of full-particle simulations. The Hall-term effect is suppressed due to the gyroviscous cancellation at scales between the ion-skin depth and ion-meandering-orbit scale, and thus ions are tied to the magnetic field. The ion frozen-in constraint is strongly broken by nongyrotropic pressure tensor effects due to ion-meandering motion, and thus the ion-dissipation region is formed at scales below the ion-meandering-orbit scale. A similar process is observed in the formation of an electron-dissipation region. These two dissipation regions are clearly observed in an out-of-plane current density profile.
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Affiliation(s)
- A Ishizawa
- National Institute for Fusion Science, Toki, Japan.
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31
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Egedal J, Oieroset M, Fox W, Lin RP. In situ discovery of an electrostatic potential, trapping electrons and mediating fast reconnection in the Earth's magnetotail. PHYSICAL REVIEW LETTERS 2005; 94:025006. [PMID: 15698186 DOI: 10.1103/physrevlett.94.025006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2004] [Revised: 08/10/2004] [Indexed: 05/24/2023]
Abstract
Anisotropic electron phase space distributions, f, measured by the Wind spacecraft in a rare crossing of a diffusion region in Earth's far magnetotail (60 Earth radii), are analyzed. We use the measured f to probe the electrostatic and magnetic geometry of the diffusion region. For the first time, the presence of a strong electrostatic potential (1 kV) within the ion diffusion region is revealed. This potential has far reaching implications for the reconnection process; it accounts for the observed acceleration of the unmagnetized ions out of the reconnection region and it causes all thermal electrons be trapped electrostatically. The trapped electron motion implies that the thermal part of the electron distributions are symmetric around v( parallel)=0: f(v( parallel),v( perpendicular)) approximately f(-v( parallel),v( perpendicular)). It follows that the field aligned currents in the diffusion region are limited and fast magnetic reconnection is mediated.
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Affiliation(s)
- J Egedal
- Massachusetts Institute of Technology, Plasma Science Fusion Center, Cambridge, Massachusetts 02139, USA
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32
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Mozer FS. Criteria for and statistics of electron diffusion regions associated with subsolar magnetic field reconnection. ACTA ACUST UNITED AC 2005. [DOI: 10.1029/2005ja011258] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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33
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Huba JD, Rudakov LI. Hall magnetic reconnection rate. PHYSICAL REVIEW LETTERS 2004; 93:175003. [PMID: 15525085 DOI: 10.1103/physrevlett.93.175003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2004] [Indexed: 05/24/2023]
Abstract
Two-dimensional Hall magnetohydrodynamic simulations are used to determine the magnetic reconnection rate in the Hall limit. The simulations are run until a steady state is achieved for four initial current sheet thicknesses: L=1,5,10, and 20c/omega(pi), where c/omega(pi) is the ion inertial length. It is found that the asymptotic (i.e., time independent) state of the system is nearly independent of the initial current sheet width. Specifically, the Hall reconnection rate is weakly dependent on the initial current layer width and is partial differential Phi/ partial differential t less, similar 0.1V(A0)B0, where Phi the reconnected flux, and V(A0) and B0 are the Alfvén velocity and magnetic field strength in the upstream region. Moreover, this rate appears to be independent of the scale length on which the electron "frozen-in" condition is broken (as long as it is <c/omega(pi)) and of the system size.
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Affiliation(s)
- J D Huba
- Plasma Physics Division, Naval Research Laboratory, Washington, DC, USA
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34
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Vaivads A, Khotyaintsev Y, André M, Retinò A, Buchert SC, Rogers BN, Décréau P, Paschmann G, Phan TD. Structure of the magnetic reconnection diffusion region from four-spacecraft observations. PHYSICAL REVIEW LETTERS 2004; 93:105001. [PMID: 15447408 DOI: 10.1103/physrevlett.93.105001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2004] [Indexed: 05/24/2023]
Abstract
Magnetic reconnection leads to energy conversion in large volumes in space but is initiated in small diffusion regions. Because of the small sizes of the diffusion regions, their crossings by spacecraft are rare. We report four-spacecraft observations of a diffusion region encounter at the Earth's magnetopause that allow us to reliably distinguish spatial from temporal features. We find that the diffusion region is stable on ion time and length scales in agreement with numerical simulations. The electric field normal to the current sheet is balanced by the Hall term in the generalized Ohm's law, E(n) approximately jxB/ne.n, thus establishing that Hall physics is dominating inside the diffusion region. The reconnection rate is fast, approximately 0.1. We show that strong parallel currents flow along the separatrices; they are correlated with observations of high-frequency Langmuir/upper hybrid waves.
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Affiliation(s)
- A Vaivads
- Swedish Institute of Space Physics, Uppsala, Sweden
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35
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Karimabadi H. On magnetic reconnection regimes and associated three-dimensional asymmetries: Hybrid, Hall-less hybrid, and Hall-MHD simulations. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2004ja010478] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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36
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Ramos JJ, Porcelli F, Verástegui R. Driven reconnection about a magnetic X-line with strong guide component. PHYSICAL REVIEW LETTERS 2002; 89:055002. [PMID: 12144447 DOI: 10.1103/physrevlett.89.055002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2001] [Indexed: 05/23/2023]
Abstract
A two-dimensional, two-fluid model is used to investigate driven magnetic reconnection in collisionless or semicollisional plasmas. The reconnection is driven by externally induced plasma flows in a background magnetic configuration that has a hyperbolic null component in the reconnection plane and a strong component, the so-called guide component, perpendicular to that plane. A dynamic solution is obtained in which the reconnection proceeds in two phases: an initial one whose characteristic rate is a fraction of the Alfvén frequency, and a later one whose rate is determined by the electron collision frequency.
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Affiliation(s)
- J J Ramos
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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37
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Mozer FS, Bale SD, Phan TD. Evidence of diffusion regions at a subsolar magnetopause crossing. PHYSICAL REVIEW LETTERS 2002; 89:015002. [PMID: 12097047 DOI: 10.1103/physrevlett.89.015002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2002] [Indexed: 05/23/2023]
Abstract
On 1 April 2001, the Polar satellite crossed a subsolar magnetopause associated with antiparallel magnetic fields. Over a width approximately 6 magnetosheath ion skin depths (approximately 3 magnetospheric ion skin depths), perpendicular ion flows different from E x B/B(2) as well as Hall magnetic and electric field signatures were observed. At a smaller scale, the electron flow decoupled from the magnetic field near a deep minimum in the magnetic field strength. Separatrices were identified as boundaries of low frequency electric field turbulence associated with density minima and parallel electric fields. The reconnection rate was less than 2% of the asymptotic Alfvén speed.
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Affiliation(s)
- F S Mozer
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
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38
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Zeiler A. Three-dimensional particle simulations of collisionless magnetic reconnection. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001ja000287] [Citation(s) in RCA: 201] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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39
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Scudder JD. Fingerprints of collisionless reconnection at the separator, I, Ambipolar-Hall signatures. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001ja000126] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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40
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Rogers BN, Denton RE, Drake JF, Shay MA. Role of dispersive waves in collisionless magnetic reconnection. PHYSICAL REVIEW LETTERS 2001; 87:195004. [PMID: 11690418 DOI: 10.1103/physrevlett.87.195004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2001] [Indexed: 05/23/2023]
Abstract
Simulations of collisionless magnetic reconnection show a dramatic enhancement of the nonlinear reconnection rate due to the formation of an open outflow region. We link the formation of this open configuration to dispersive whistler and kinetic Alfvén wave dynamics at small scales. The roles of these two waves are controlled by two dimensionless parameters, which allow us to identify regions of fast and slow reconnection.
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Affiliation(s)
- B N Rogers
- Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755, USA
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Pritchett PL. Collisionless magnetic reconnection in a three-dimensional open system. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001ja000016] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Oieroset M, Phan TD, Fujimoto M, Lin RP, Lepping RP. In situ detection of collisionless reconnection in the Earth's magnetotail. Nature 2001; 412:414-7. [PMID: 11473310 DOI: 10.1038/35086520] [Citation(s) in RCA: 411] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Magnetic reconnection is the process by which magnetic field lines of opposite polarity reconfigure to a lower-energy state, with the release of magnetic energy to the surroundings. Reconnection at the Earth's dayside magnetopause and in the magnetotail allows the solar wind into the magnetosphere. It begins in a small 'diffusion region', where a kink in the newly reconnected lines produces jets of plasma away from the region. Although plasma jets from reconnection have previously been reported, the physical processes that underlie jet formation have remained poorly understood because of the scarcity of in situ observations of the minuscule diffusion region. Theoretically, both resistive and collisionless processes can initiate reconnection, but which process dominates in the magnetosphere is still debated. Here we report the serendipitous encounter of the Wind spacecraft with an active reconnection diffusion region, in which are detected key processes predicted by models of collisionless reconnection. The data therefore demonstrate that collisionless reconnection occurs in the magnetotail.
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Affiliation(s)
- M Oieroset
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA.
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Deng XH, Matsumoto H. Rapid magnetic reconnection in the Earth's magnetosphere mediated by whistler waves. Nature 2001; 410:557-60. [PMID: 11279487 DOI: 10.1038/35069018] [Citation(s) in RCA: 230] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Magnetic reconnection has a crucial role in a variety of plasma environments in providing a mechanism for the fast release of stored magnetic energy. During reconnection the plasma forms a 'magnetic nozzle', like the nozzle of a hose, and the rate is controlled by how fast plasma can flow out of the nozzle. But the traditional picture of reconnection has been unable to explain satisfactorily the short timescales associated with the energy release, because the flow is mediated by heavy ions with a slow resultant velocity. Recent theoretical work has suggested that the energy release is instead mediated by electrons in waves called 'whistlers', which move much faster for a given perturbation of the magnetic field because of their smaller mass. Moreover, the whistler velocity and associated plasma velocity both increase as the 'nozzle' becomes narrower. A narrower nozzle therefore no longer reduces the total plasma flow-the outflow is independent of the size of the nozzle. Here we report observations demonstrating that reconnection in the magnetosphere is driven by whistlers, in good agreement with the theoretical predictions.
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Pritchett PL. Geospace Environment Modeling magnetic reconnection challenge: Simulations with a full particle electromagnetic code. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/1999ja001006] [Citation(s) in RCA: 300] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Ma ZW, Bhattacharjee A. Hall magnetohydrodynamic reconnection: The Geospace Environment Modeling challenge. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/1999ja001004] [Citation(s) in RCA: 142] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Hesse M, Birn J, Kuznetsova M. Collisionless magnetic reconnection: Electron processes and transport modeling. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/1999ja001002] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Birn J, Drake JF, Shay MA, Rogers BN, Denton RE, Hesse M, Kuznetsova M, Ma ZW, Bhattacharjee A, Otto A, Pritchett PL. Geospace Environmental Modeling (GEM) Magnetic Reconnection Challenge. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/1999ja900449] [Citation(s) in RCA: 991] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Otto A. Geospace Environment Modeling (GEM) magnetic reconnection challenge: MHD and Hall MHD-constant and current dependent resistivity models. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/1999ja001005] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Birn J, Hesse M. Geospace Environment Modeling (GEM) magnetic reconnection challenge: Resistive tearing, anisotropic pressure and Hall effects. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/1999ja001001] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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