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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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2
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Kitamura N, Amano T, Omura Y, Boardsen SA, Gershman DJ, Miyoshi Y, Kitahara M, Katoh Y, Kojima H, Nakamura S, Shoji M, Saito Y, Yokota S, Giles BL, Paterson WR, Pollock CJ, Barrie AC, Skeberdis DG, Kreisler S, Le Contel O, Russell CT, Strangeway RJ, Lindqvist PA, Ergun RE, Torbert RB, Burch JL. Direct observations of energy transfer from resonant electrons to whistler-mode waves in magnetosheath of Earth. Nat Commun 2022; 13:6259. [PMID: 36307443 PMCID: PMC9616889 DOI: 10.1038/s41467-022-33604-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 09/22/2022] [Indexed: 11/30/2022] Open
Abstract
Electromagnetic whistler-mode waves in space plasmas play critical roles in collisionless energy transfer between the electrons and the electromagnetic field. Although resonant interactions have been considered as the likely generation process of the waves, observational identification has been extremely difficult due to the short time scale of resonant electron dynamics. Here we show strong nongyrotropy, which rotate with the wave, of cyclotron resonant electrons as direct evidence for the locally ongoing secular energy transfer from the resonant electrons to the whistler-mode waves using ultra-high temporal resolution data obtained by NASA’s Magnetospheric Multiscale (MMS) mission in the magnetosheath. The nongyrotropic electrons carry a resonant current, which is the energy source of the wave as predicted by the nonlinear wave growth theory. This result proves the nonlinear wave growth theory, and furthermore demonstrates that the degree of nongyrotropy, which cannot be predicted even by that nonlinear theory, can be studied by observations. Excitation of whistler-mode waves by cyclotron instability is considered as the likely generation process of the waves. Here, the authors show direct observational evidence for locally ongoing secular energy transfer from the resonant electrons to the whistler-mode waves in Earth’s magnetosheath.
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Affiliation(s)
- N Kitamura
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan. .,Department of Earth and Planetary Science, Graduate School of Science, the University of Tokyo, Tokyo, Japan.
| | - T Amano
- Department of Earth and Planetary Science, Graduate School of Science, the University of Tokyo, Tokyo, Japan
| | - Y Omura
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan
| | - S A Boardsen
- NASA Goddard Space Flight Center, Greenbelt, MD, USA.,Goddard Planetary Heliophysics Institute, University of Maryland, Baltimore County, MD, USA
| | - D J Gershman
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - Y Miyoshi
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - M Kitahara
- Department of Geophysics, Graduate school of Science, Tohoku University, Sendai, Japan
| | - Y Katoh
- Department of Geophysics, Graduate school of Science, Tohoku University, Sendai, Japan
| | - H Kojima
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan
| | - S Nakamura
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - M Shoji
- Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan
| | - Y Saito
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - S Yokota
- Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - B L Giles
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - W R Paterson
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | | | - A C Barrie
- NASA Goddard Space Flight Center, Greenbelt, MD, USA.,Aurora Engineering, Potomac, MD, USA
| | - D G Skeberdis
- NASA Goddard Space Flight Center, Greenbelt, MD, USA.,a.i. solutions Inc, Lanham, MD, USA
| | - S Kreisler
- NASA Goddard Space Flight Center, Greenbelt, MD, USA.,Aurora Engineering, Potomac, MD, USA
| | - O Le Contel
- Laboratoire de Physique des Plasmas, CNRS/Sorbonne Université/Université Paris-Saclay/Observatoire de Paris/Ecole Polytechnique Institut Polytechnique de Paris, Paris, France
| | - C T Russell
- Department of Earth, Planetary, and Space Science, University of California, Los Angeles, CA, USA
| | - R J Strangeway
- Department of Earth, Planetary, and Space Science, University of California, Los Angeles, CA, USA
| | | | - R E Ergun
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - R B Torbert
- Department of Physics, University of New Hampshire, Durham, NH, USA.,Southwest Research Institute, San Antonio, TX, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, TX, USA
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3
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Direct observations of anomalous resistivity and diffusion in collisionless plasma. Nat Commun 2022; 13:2954. [PMID: 35618713 PMCID: PMC9135766 DOI: 10.1038/s41467-022-30561-8] [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: 11/14/2019] [Accepted: 05/04/2022] [Indexed: 11/29/2022] Open
Abstract
Coulomb collisions provide plasma resistivity and diffusion but in many low-density astrophysical plasmas such collisions between particles are extremely rare. Scattering of particles by electromagnetic waves can lower the plasma conductivity. Such anomalous resistivity due to wave-particle interactions could be crucial to many processes, including magnetic reconnection. It has been suggested that waves provide both diffusion and resistivity, which can support the reconnection electric field, but this requires direct observation to confirm. Here, we directly quantify anomalous resistivity, viscosity, and cross-field electron diffusion associated with lower hybrid waves using measurements from the four Magnetospheric Multiscale (MMS) spacecraft. We show that anomalous resistivity is approximately balanced by anomalous viscosity, and thus the waves do not contribute to the reconnection electric field. However, the waves do produce an anomalous electron drift and diffusion across the current layer associated with magnetic reconnection. This leads to relaxation of density gradients at timescales of order the ion cyclotron period, and hence modifies the reconnection process. It is suggested that waves can provide both diffusion and resistivity that can potentially support the reconnection electric field in low-density astrophysical plasmas. Here, the authors show, using direct spacecraft measurements, that the waves contribute to anomalous diffusion but do not contribute to the reconnection electric field.
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4
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Barrie AC, Schiff C, Gershman DJ, Giles BL, Rand D. Calibrating Electrostatic Deflection of Charged Particle Sensors Using Ambient Plasma Measurements. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2021; 126:e2021JA029149. [PMID: 35860602 PMCID: PMC9285780 DOI: 10.1029/2021ja029149] [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: 01/22/2021] [Revised: 06/14/2021] [Accepted: 06/15/2021] [Indexed: 06/15/2023]
Abstract
As space-based charged particle measurement pushes the technical envelope, resolution, both spatially and temporally, is ever improving. As such, the knowledge of the associated error must also improve. We present a method for correlating data collected from multiple sensors at different times in order to estimate the pointing error of each sensor. The method is demonstrated using flight data from the Dual Ion Spectrometer suite, part of the Fast Plasma Investigation on the NASA's Magnetospheric Multiscale mission. By looking at signals with sharp features in the direction of spacecraft spin, the relative error in look direction between sensors can be estimated with sub-degree precision, roughly 20 times better than the native resolution in the azimuthal (spin) direction. These sharp features appear in nature often enough that a sufficiently large sample size can be identified, using an automated filter of routine science data, to calibrate the system, or post correct measured data. The relative pointing error can then be trended over time to monitor the evolution/aging of the measurement system. These data inform calibration/correction methods, should the error grow to a point where science quality is adversely affected.
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Affiliation(s)
| | | | | | | | - David Rand
- NASA Goddard Space Flight CenterGreenbeltMDUSA
- A. I. SolutionsGreenbeltMDUSA
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5
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Chen LJ, Wang S, Le Contel O, Rager A, Hesse M, Drake J, Dorelli J, Ng J, Bessho N, Graham D, Wilson LB, Moore T, Giles B, Paterson W, Lavraud B, Genestreti K, Nakamura R, Khotyaintsev YV, Ergun RE, Torbert RB, Burch J, Pollock C, Russell CT, Lindqvist PA, Avanov L. Lower-Hybrid Drift Waves Driving Electron Nongyrotropic Heating and Vortical Flows in a Magnetic Reconnection Layer. PHYSICAL REVIEW LETTERS 2020; 125:025103. [PMID: 32701350 DOI: 10.1103/physrevlett.125.025103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 06/11/2020] [Indexed: 06/11/2023]
Abstract
We report measurements of lower-hybrid drift waves driving electron heating and vortical flows in an electron-scale reconnection layer under a guide field. Electrons accelerated by the electrostatic potential of the waves exhibit perpendicular and nongyrotropic heating. The vortical flows generate magnetic field perturbations comparable to the guide field magnitude. The measurements reveal a new regime of electron-wave interaction and how this interaction modifies the electron dynamics in the reconnection layer.
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Affiliation(s)
- L-J Chen
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - S Wang
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
- University of Maryland, College Park, Maryland 20747, USA
| | - O Le Contel
- CNRS/Ecole Polytechnique/Sorbonne Université/Univ. Paris Sud/Observatoire de Paris, Paris F91128, France
| | - A Rager
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - M Hesse
- University of Bergen, Bergen 5020, Norway
| | - J Drake
- University of Maryland, College Park, Maryland 20747, USA
| | - J Dorelli
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - J Ng
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
- University of Maryland, College Park, Maryland 20747, USA
| | - N Bessho
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
- University of Maryland, College Park, Maryland 20747, USA
| | - D Graham
- Swedish Institute of Space Physics, Uppsala SE-75121, Sweden
| | - Lynn B Wilson
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - T Moore
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - B Giles
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - W Paterson
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - B Lavraud
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse (UPS), CNRS, CNES, Toulouse 31027 Cedex 4, France
| | - K Genestreti
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - R Nakamura
- Space Research Institute, Austrian Academy of Sciences, Graz A-8042, Austria
| | | | - R E Ergun
- University of Colorado, Boulder, Colorado 80305, USA
| | - R B Torbert
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - J Burch
- Southwest Research Institute, San Antonio, Texas 78238, USA
| | - C Pollock
- Denali Scientific, Healy, Alaska 99743, USA
| | - C T Russell
- University of California, Los Angeles, Los Angeles, California 90095, USA
| | - P-A Lindqvist
- KTH Royal Institute of Technology, Stockholm SE-11428, Sweden
| | - L Avanov
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
- University of Maryland, College Park, Maryland 20747, USA
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6
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Khotyaintsev YV, Graham DB, Steinvall K, Alm L, Vaivads A, Johlander A, Norgren C, Li W, Divin A, Fu HS, Hwang KJ, Burch JL, Ahmadi N, Le Contel O, Gershman DJ, Russell CT, Torbert RB. Electron Heating by Debye-Scale Turbulence in Guide-Field Reconnection. PHYSICAL REVIEW LETTERS 2020; 124:045101. [PMID: 32058767 DOI: 10.1103/physrevlett.124.045101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 11/22/2019] [Indexed: 06/10/2023]
Abstract
We report electrostatic Debye-scale turbulence developing within the diffusion region of asymmetric magnetopause reconnection with a moderate guide field using observations by the Magnetospheric Multiscale mission. We show that Buneman waves and beam modes cause efficient and fast thermalization of the reconnection electron jet by irreversible phase mixing, during which the jet kinetic energy is transferred into thermal energy. Our results show that the reconnection diffusion region in the presence of a moderate guide field is highly turbulent, and that electrostatic turbulence plays an important role in electron heating.
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Affiliation(s)
| | - D B Graham
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
| | - K Steinvall
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
| | - L Alm
- Swedish Institute of Space Physics, Uppsala 75121, Sweden
| | - A Vaivads
- Department of Space and Plasma Physics, School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, Stockholm 11428, Sweden
| | - A Johlander
- Department of Physics, University of Helsinki, Helsinki 00014, Finland
| | - C Norgren
- University of Bergen, Bergen 5007, Norway
| | - W Li
- State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China
| | - A Divin
- Earth Physics Department, St. Petersburg State University, St. Petersburg 198504, Russia
| | - H S Fu
- School of Space and Environment, Beihang University, Beijing 100083, China
| | - K-J Hwang
- Southwest Research Institute, San Antonio, Texas 78228, USA
| | - J L Burch
- Southwest Research Institute, San Antonio, Texas 78228, USA
| | - N Ahmadi
- Laboratory of Atmospheric and Space Physics, University of Colorado, Boulder, Colorado 80303, USA
| | - O Le Contel
- Laboratoire de Physique des Plasmas, CNRS, Ecole Polytechnique, Sorbonne Université, Université Paris-Sud, and Observatoire de Paris, Paris, F-75252 Paris Cedex 05, France
| | - D J Gershman
- NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
| | - C T Russell
- University of California, Los Angeles, California 90095, USA
| | - R B Torbert
- University of New Hampshire, Durham, New Hampshire 03824, USA
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7
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Electron Bernstein waves driven by electron crescents near the electron diffusion region. Nat Commun 2020; 11:141. [PMID: 31919351 PMCID: PMC6952373 DOI: 10.1038/s41467-019-13920-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 12/05/2019] [Indexed: 11/08/2022] Open
Abstract
The Magnetospheric Multiscale (MMS) spacecraft encounter an electron diffusion region (EDR) of asymmetric magnetic reconnection at Earth's magnetopause. The EDR is characterized by agyrotropic electron velocity distributions on both sides of the neutral line. Various types of plasma waves are produced by the magnetic reconnection in and near the EDR. Here we report large-amplitude electron Bernstein waves (EBWs) at the electron-scale boundary of the Hall current reversal. The finite gyroradius effect of the outflow electrons generates the crescent-shaped agyrotropic electron distributions, which drive the EBWs. The EBWs propagate toward the central EDR. The amplitude of the EBWs is sufficiently large to thermalize and diffuse electrons around the EDR. The EBWs contribute to the cross-field diffusion of the electron-scale boundary of the Hall current reversal near the EDR.
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8
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Dokgo K, Hwang K, Burch JL, Choi E, Yoon PH, Sibeck DG, Graham DB. High-Frequency Wave Generation in Magnetotail Reconnection: Nonlinear Harmonics of Upper Hybrid Waves. GEOPHYSICAL RESEARCH LETTERS 2019; 46:7873-7882. [PMID: 31598022 PMCID: PMC6774311 DOI: 10.1029/2019gl083361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 06/12/2019] [Accepted: 06/30/2019] [Indexed: 06/10/2023]
Abstract
MMS3 spacecraft passed the vicinity of the electron diffusion region of magnetotail reconnection on 3 July 2017, observing discrepancies between perpendicular electron bulk velocities and E → × B → drift, and agyrotropic electron crescent distributions. Analyzing linear wave dispersions, Burch et al. (2019, https://doi.org/10.1029/2019GL082471) showed the electron crescent generates high-frequency waves. We investigate harmonics of upper-hybrid (UH) waves using both observation and particle-in-cell (PIC) simulation, and the generation of electromagnetic radiation from PIC simulation. Harmonics of UH are linearly polarized and propagate along the perpendicular direction to the ambient magnetic field. Compared with two-dimensional PIC simulation and nonlinear kinetic theory, we show that the nonlinear beam-plasma interaction between the agyrotropic electrons and the core electrons generates harmonics of UH. Moreover, PIC simulation shows that agyrotropic electron beam can lead to electromagnetic (EM) radiation at the plasma frequency and harmonics.
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Affiliation(s)
| | | | | | - Eunjin Choi
- Southwest Research InstituteSan AntonioTXUSA
| | - Peter H. Yoon
- Institute for Physical Science and TechnologyUniversity of MarylandCollege ParkMDUSA
- School of Space ResearchKyung Hee UniversityYonginSouth Korea
- Korea Astronomy and Space Science InstituteDaejeonSouth Korea
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9
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Liu YH, Hesse M, Li TC, Kuznetsova M, Le A. Orientation and Stability of Asymmetric Magnetic Reconnection X Line. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2018; 123:4908-4920. [PMID: 30364510 PMCID: PMC6196328 DOI: 10.1029/2018ja025410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Accepted: 05/18/2018] [Indexed: 06/08/2023]
Abstract
The orientation and stability of the reconnection x line in asymmetric geometry is studied using three-dimensional (3-D) particle-in-cell simulations. We initiate reconnection at the center of a large simulation domain to minimize the boundary effect. The resulting x line has sufficient freedom to develop along an optimal orientation, and it remains laminar. Companion 2-D simulations indicate that this x line orientation maximizes the reconnection rate. The divergence of the nongyrotropic pressure tensor breaks the frozen-in condition, consistent with its 2-D counterpart. We then design 3-D simulations with one dimension being short to fix the x line orientation but long enough to allow the growth of the fastest growing oblique tearing modes. This numerical experiment suggests that reconnection tends to radiate secondary oblique tearing modes if it is externally (globally) forced to proceed along an orientation not favored by the local physics. The development of oblique structure easily leads to turbulence inside small periodic systems.
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Affiliation(s)
- Yi-Hsin Liu
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH, USA
| | - M Hesse
- Department of Physics and Technology, University of Bergen, Bergen, Norway
- Southwest Research Institute, San Antonio, TX, USA
| | - T C Li
- Department of Physics and Astronomy, Dartmouth College, Hanover, NH, USA
| | - M Kuznetsova
- NASA-Goddard Space Flight Center, Greenbelt, MD, USA
| | - A Le
- Los Alamos National Laboratory, Los Alamos, NM, USA
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10
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Electron magnetic reconnection without ion coupling in Earth's turbulent magnetosheath. Nature 2018; 557:202-206. [PMID: 29743689 DOI: 10.1038/s41586-018-0091-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 01/30/2018] [Indexed: 11/08/2022]
Abstract
Magnetic reconnection in current sheets is a magnetic-to-particle energy conversion process that is fundamental to many space and laboratory plasma systems. In the standard model of reconnection, this process occurs in a minuscule electron-scale diffusion region1,2. On larger scales, ions couple to the newly reconnected magnetic-field lines and are ejected away from the diffusion region in the form of bi-directional ion jets at the ion Alfvén speed3-5. Much of the energy conversion occurs in spatially extended ion exhausts downstream of the diffusion region 6 . In turbulent plasmas, which contain a large number of small-scale current sheets, reconnection has long been suggested to have a major role in the dissipation of turbulent energy at kinetic scales7-11. However, evidence for reconnection plasma jetting in small-scale turbulent plasmas has so far been lacking. Here we report observations made in Earth's turbulent magnetosheath region (downstream of the bow shock) of an electron-scale current sheet in which diverging bi-directional super-ion-Alfvénic electron jets, parallel electric fields and enhanced magnetic-to-particle energy conversion were detected. Contrary to the standard model of reconnection, the thin reconnecting current sheet was not embedded in a wider ion-scale current layer and no ion jets were detected. Observations of this and other similar, but unidirectional, electron jet events without signatures of ion reconnection reveal a form of reconnection that can drive turbulent energy transfer and dissipation in electron-scale current sheets without ion coupling.
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11
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Burch JL, Webster JM, Genestreti KJ, Torbert RB, Giles BL, Fuselier SA, Dorelli JC, Rager AC, Phan TD, Allen RC, Chen L, Wang S, Le Contel O, Russell CT, Strangeway RJ, Ergun RE, Jaynes AN, Lindqvist P, Graham DB, Wilder FD, Hwang K, Goldstein J. Wave Phenomena and Beam-Plasma Interactions at the Magnetopause Reconnection Region. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2018; 123:1118-1133. [PMID: 29938153 PMCID: PMC5993346 DOI: 10.1002/2017ja024789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 12/28/2017] [Accepted: 01/10/2018] [Indexed: 06/08/2023]
Abstract
This paper reports on Magnetospheric Multiscale observations of whistler mode chorus and higher-frequency electrostatic waves near and within a reconnection diffusion region on 23 November 2016. The diffusion region is bounded by crescent-shaped electron distributions and associated dissipation just upstream of the X-line and by magnetic field-aligned currents and electric fields leading to dissipation near the electron stagnation point. Measurements were made southward of the X-line as determined by southward directed ion and electron jets. We show that electrostatic wave generation is due to magnetosheath electron beams formed by the electron jets as they interact with a cold background plasma and more energetic population of magnetospheric electrons. On the magnetosphere side of the X-line the electron beams are accompanied by a strong perpendicular electron temperature anisotropy, which is shown to be the source of an observed rising-tone whistler mode chorus event. We show that the apex of the chorus event and the onset of electrostatic waves coincide with the opening of magnetic field lines at the electron stagnation point.
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Affiliation(s)
- J. L. Burch
- Southwest Research InstituteSan AntonioTXUSA
| | - J. M. Webster
- Department of Physics and AstronomyRice UniversityHoustonTXUSA
| | | | - R. B. Torbert
- Southwest Research InstituteSan AntonioTXUSA
- Department of PhysicsUniversity of New HampshireDurhamNHUSA
| | - B. L. Giles
- NASA, Goddard Space Flight CenterGreenbeltMDUSA
| | | | | | - A. C. Rager
- NASA, Goddard Space Flight CenterGreenbeltMDUSA
- Department of PhysicsCatholic University of AmericaWashingtonDCUSA
| | - T. D. Phan
- Space Sciences LaboratoryUniversity of CaliforniaBerkeleyCAUSA
| | - R. C. Allen
- Applied Physics LaboratoryThe Johns Hopkins UniversityLaurelMDUSA
| | - L.‐J. Chen
- Department of AstronomyUniversity of MarylandCollege ParkMDUSA
| | - S. Wang
- Department of AstronomyUniversity of MarylandCollege ParkMDUSA
| | - O. Le Contel
- Laboratoire de Physique des PlasmasCNRS, Ecole Polytechnique, UPMC University Paris 06, Université Paris‐Sud, Observatoire de ParisParisFrance
| | - C. T. Russell
- Earth and Planetary SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - R. J. Strangeway
- Earth and Planetary SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - R. E. Ergun
- LASPUniversity of Colorado BoulderBoulderCOUSA
| | - A. N. Jaynes
- Department of Physics and AstronomyUniversity of IowaIowa CityIAUSA
| | | | | | | | - K.‐J. Hwang
- Southwest Research InstituteSan AntonioTXUSA
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