Observations of an Electron Diffusion Region in Symmetric Reconnection with Weak Guide Field

Zhou, Meng; Deng, Xiaohua; Zhong, Zhihong; Pang, Y.; Tang, Rongxin; El‐Alaoui, M.; Walker, Raymond J.; Russell, C. T.; Lapenta, Giovanni; Strangeway, R. J.; Torbert, R. B.; Burch, J. L.; Paterson, W. R.; Giles, B. L.; Khotyaintsev, Yuri V.; Ergun, R. E.; Lindqvist, Per‐Arne

doi:10.3847/1538-4357/aaf16f

Cited by 93 publications

(136 citation statements)

References 45 publications

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“…Similar temperature anisotropy and bidirectional electron velocity distributions have been found in the inflow region of the diffusion region (Chen et al, 2009; Huang et al, ; Zhou et al, ). It is suggested that acceleration by parallel electric field causes the temperature anisotropy in the inflow region (Egedal et al, ).…”

Section: Novel Properties Of the Idrsupporting

confidence: 65%

“…MMS observed an EDR in the magnetotail on 10 August 2017 (Zhou et al, ). This EDR was embedded within a much larger IDR.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…This means that electrons were mostly nonadiabatic and suffered pitch angle mixing/scattering. Therefore, the disappearance of anisotropy within the IDR was probably caused by the pitch angle mixing/scattering due to the highly curved magnetic field lines, which has been demonstrated to cause the isotropic and gyrotropic electron distributions in the EDR (Lavraud et al, ; Zhou et al, ).…”

Section: Novel Properties Of the Idrmentioning

confidence: 99%

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Sub‐ion‐scale Dynamics of the Ion Diffusion Region in the Magnetotail: MMS Observations

et al. 2019

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This paper reports magnetospheric multiscale (MMS) observations of the sub‐ion‐scale dynamics within the ion diffusion region (IDR) in the Earth's magnetotail. MMS crossed the IDR from the southern to the northern hemisphere, at about two ion inertial length earthward of the X line with a small guide field. Electrons were anisotropic in the inflow region of the IDR and turned into isotropic within the IDR. The isotropization of the electrons was probably due to the pitch angle scattering in highly curved magnetic field lines. We suggest that the thickness of the electron isotropic region strongly depends on the horizontal distance to the X line. The out‐of‐plane current bifurcated in the IDR. It peaked at the boundaries between the inflow and outflow electrons around the separatrices. Magnetic energy conversion and dissipation predominantly occurred at the peak of the out‐of‐plane current instead of at the neutral sheet center where BL = 0. Both the energy dissipation and normal electric field EN exhibited evident asymmetry with respect to the neutral sheet. The energy dissipation was larger around the northern separatrix than around the southern separatrix. The electric field EN showed a tripolar variation across the neutral sheet, that is, a unipolar EN around the southern separatrix and a bipolar EN around the northern separatrix. The reasons and implications of these asymmetries are discussed.

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Section: Novel Properties Of the Idrsupporting

confidence: 65%

“…MMS observed an EDR in the magnetotail on 10 August 2017 (Zhou et al, ). This EDR was embedded within a much larger IDR.…”

Section: Discussion and Summarymentioning

confidence: 99%

Section: Novel Properties Of the Idrmentioning

confidence: 99%

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Sub‐ion‐scale Dynamics of the Ion Diffusion Region in the Magnetotail: MMS Observations

et al. 2019

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“…Here we will present only the data relevant to our analysis. For more details about this event, see the description of Zhou et al ().…”

Section: Resultsmentioning

confidence: 99%

Polynomial Reconstruction of the Reconnection Magnetic Field Observed by Multiple Spacecraft

et al. 2020

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We describe methods for polynomial reconstruction of the magnetic field close to a cluster of spacecraft and apply that to reconstruction of the magnetic field observed during a magnetic reconnection event on 10 August 2017 by the Magnetospheric Multiscale spacecraft. Four different models are described, which vary in complexity between a 12‐parameter linear model, which has only linear variation with respect to the spatial coordinates, and a 27‐parameter quadratic model, which has the full quadratic expansion except that the second derivative with respect to the Minimum Directional Derivative minimum gradient coordinate m has been neglected. In contrast to previous reconstruction techniques, these reconstructions can be found using only the magnetic field and current density measured at a single time by the cluster of spacecraft. The equations satisfying ∇·boldB=0 are satisfied exactly, while the equations specifying the model fields at the spacecraft locations are satisfied for most models in a best least squares sense. For this magnetotail event, the models have very small errors in magnetic field components ( <0.1 nT) at a distance from the nearest spacecraft on the order of the spacecraft separation, Lsc, here equal to 20.5 km. The magnetic structures found using the quadratic models are very time dependent, with a stretched field leading to plasmoid formation at one point in time.

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“…The EDR had been difficult to identify mainly because of its small size in conjunction with the limited ©2019. Another magnetotail EDR event reported by Zhou et al (2019) also exhibited J▪E′ > 0, electron agyrotropy, and super-Alfvénic electron jets. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.…”

Section: Introductionmentioning

confidence: 83%

Electron Vorticity Indicative of the Electron Diffusion Region of Magnetic Reconnection

Hwang

Choi

Dokgo

et al. 2019

Geophysical Research Letters

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While vorticity defined as the curl of the velocity has been broadly used in fluid and plasma physics, this quantity has been underutilized in space physics due to low time resolution observations. We report Magnetospheric Multiscale (MMS) observations of enhanced electron vorticity in the vicinity of the electron diffusion region of magnetic reconnection. On 11 July 2017 MMS traversed the magnetotail current sheet, observing tailward‐to‐earthward outflow reversal, current‐carrying electron jets in the direction along the electron meandering motion or out‐of‐plane direction, agyrotropic electron distribution functions, and dissipative signatures. At the edge of the electron jets, the electron vorticity increased with magnitudes greater than the electron gyrofrequency. The out‐of‐plane velocity shear along distance from the current sheet leads to the enhanced vorticity. This, in turn, contributes to the magnetic field perturbations observed by MMS. These observations indicate that electron vorticity can act as a proxy for delineating the electron diffusion region of magnetic reconnection.

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Observations of an Electron Diffusion Region in Symmetric Reconnection with Weak Guide Field

Cited by 93 publications

References 45 publications

Sub‐ion‐scale Dynamics of the Ion Diffusion Region in the Magnetotail: MMS Observations

Sub‐ion‐scale Dynamics of the Ion Diffusion Region in the Magnetotail: MMS Observations

Polynomial Reconstruction of the Reconnection Magnetic Field Observed by Multiple Spacecraft

Electron Vorticity Indicative of the Electron Diffusion Region of Magnetic Reconnection

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