Magnetospheric Multiscale Observations of the Electron Diffusion Region of Large Guide Field Magnetic Reconnection

Eriksson, S.; Wilder, F. D.; Ergun, R. E.; Schwartz, Steven J.; Cassak, P. A.; Burch, J. L.; Chen, Li‐Jen; Torbert, R. B.; Phan, T. D.; Lavraud, B.; Goodrich, K.; Holmes, J. C.; Stawarz, J. E.; Sturner, A. P.; Malaspina, D.; Usanova, Maria; Trattner, K. J.; Strangeway, R. J.; Russell, C. T.; Pollock, C. J.; Giles, B. L.; Hesse, M.; Lindqvist, Per‐Arne; Drake, J. F.; Shay, M. A.; Nakamura, R.; Marklund, Göran

doi:10.1103/physrevlett.117.015001

Cited by 77 publications

(109 citation statements)

References 31 publications

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“…Many signatures of the inner diffusion region are observed in this region, including an intense and narrow out‐of‐plane electron current, an intense broad region of electron anisotropy with T e ,∥ < T e ,⊥ followed by T e ,∥ ≫ T e ,⊥ (Figures m and l), and a moderate narrow region of electron agyrotropy,

\overset{J}{true} \cdot {\overset{E}{true}}^{'} > 0

, all of which are discussed in the next section. As is shown in Figure c, the current near the B L reversal is largely field aligned, which is common in MMS observations of asymmetric guide field reconnection (Burch & Phan, ; Chen et al, ; Ergun et al, ; Eriksson et al, ; Genestreti et al, ). It is unlikely that MMS crossed the center of the reconnection site, or the exact X‐point, since the Hall field

B_{M} < (〈〉, B_{M, guide})

remained large throughout the B L reversal interval.…”

Section: Large‐scale Observations During the Magnetopause Crossingsupporting

confidence: 59%

“…Nakamura et al (), Price et al (, ), and Le et al () have all recently performed 3‐d PIC simulations of MMS EDR events. Nakamura et al () analyzed a large‐scale simulation of the very large guide field Kelvin‐Helmholtz vortex reconnection event of Eriksson et al (). Both the simulation and the data showed parallel out‐of‐plane electric fields in the

\overset{J}{true} \cdot {\overset{E}{true}}^{'} > 0

region that were several times larger than what is expected for the nominal fast reconnection rate of 0.1.…”

Section: Introductionmentioning

confidence: 99%

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MMS Observation of Asymmetric Reconnection Supported by 3‐D Electron Pressure Divergence

et al. 2018

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We identify the electron diffusion region (EDR) of a guide field dayside reconnection site encountered by the Magnetospheric Multiscale (MMS) mission and estimate the terms in generalized Ohm's law that controlled energy conversion near the X‐point. MMS crossed the moderate‐shear (∼130°) magnetopause southward of the exact X‐point. MMS likely entered the magnetopause far from the X‐point, outside the EDR, as the size of the reconnection layer was less than but comparable to the magnetosheath proton gyroradius, and also as anisotropic gyrotropic “outflow” crescent electron distributions were observed. MMS then approached the X‐point, where all four spacecraft simultaneously observed signatures of the EDR, for example, an intense out‐of‐plane electron current, moderate electron agyrotropy, intense electron anisotropy, nonideal electric fields, and nonideal energy conversion. We find that the electric field associated with the nonideal energy conversion is (a) well described by the sum of the electron inertial and pressure divergence terms in generalized Ohms law though (b) the pressure divergence term dominates the inertial term by roughly a factor of 5:1, (c) both the gyrotropic and agyrotropic pressure forces contribute to energy conversion at the X‐point, and (d) both out‐of‐the‐reconnection‐plane gradients (∂/∂M) and in‐plane (∂/∂L,N) in the pressure tensor contribute to energy conversion near the X‐point. This indicates that this EDR had some electron‐scale structure in the out‐of‐plane direction during the time when (and at the location where) the reconnection site was observed.

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\overset{J}{true} \cdot {\overset{E}{true}}^{'} > 0

B_{M} < (〈〉, B_{M, guide})

remained large throughout the B L reversal interval.…”

Section: Large‐scale Observations During the Magnetopause Crossingsupporting

confidence: 59%

\overset{J}{true} \cdot {\overset{E}{true}}^{'} > 0

region that were several times larger than what is expected for the nominal fast reconnection rate of 0.1.…”

Section: Introductionmentioning

confidence: 99%

MMS Observation of Asymmetric Reconnection Supported by 3‐D Electron Pressure Divergence

et al. 2018

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“…The clear peaks of curl of E′ suggests that the electrons were not frozen-in to the magnetic field within this region (Goldman et al, 2016;Zhou et al, 2017). It has been reported that large guide field can magnetize electrons within the EDR (Eriksson et al, 2016;Zhou et al, 2017). It has been reported that large guide field can magnetize electrons within the EDR (Eriksson et al, 2016;Zhou et al, 2017).…”

Section: An Active X Line In the Exhaustmentioning

confidence: 89%

Observations of a Kinetic‐Scale Magnetic Hole in a Reconnection Diffusion Region

Zhong

Zhou

Huang

et al. 2019

Geophysical Research Letters

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Magnetic holes have been widely observed in various space plasma systems. The origin of magnetic holes and their influence to background plasma are under debate. In this paper, we show a kinetic‐scale electron vortex magnetic hole in a nonideal region of an active X line, which was observed by the Magnetospheric Multiscale mission at the dayside magnetopause. Intense current and nonideal electric field in the electron frame were observed within the magnetic hole, which led to a strong energy dissipation. Thus, the electron vortex magnetic hole probably provided an additional energy dissipation channel besides the electron diffusion region adjacent to the hole. We suggest that magnetic reconnection provided favorable conditions for the formation of this kinetic‐scale magnetic hole and is an important source of magnetic holes in space plasma.

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“…Since its launch on 12 March 2015, Magnetospheric Multiscale (MMS) has observed magnetic reconnection at the dayside MP many times (e.g., Burch et al, ; Lavraud et al, ; Zhou et al, , ). In particular, asymmetric reconnection with a large guide field has been studied by Burch and Phan () and Eriksson et al (). Since these studies focused on the physics in the vicinity of the EDR, details of the ion diffusion region (IDR) in large guide field reconnection were not investigated.…”

Section: Introductionmentioning

confidence: 99%

Magnetospheric Multiscale Observations of an Ion Diffusion Region With Large Guide Field at the Magnetopause: Current System, Electron Heating, and Plasma Waves

et al. 2018

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We report Magnetospheric Multiscale (MMS) observations of a reconnecting current sheet in the presence of a weak density asymmetry with large guide field at the dayside magnetopause. An ion diffusion region (IDR) was detected associated with this current sheet. Parallel current dominated over the perpendicular current in the IDR, as found in previous studies of component reconnection. Electrons were preferentially heated parallel to the magnetic field within the IDR. The heating was manifested as a flattop distribution below 400 eV. Two types of electromagnetic electron whistler waves were observed within the regions where electrons were heated. One type of whistler wave was associated with nonlinear structures in E|| with amplitudes up to 20 mV/m. The other type was not associated with any structures in E||. Poynting fluxes of these two types of whistler waves were directed away from the X‐line. We suggest that the nonlinear evolution of the oblique whistler waves gave rise to the solitary structures in E||. There was a perpendicular super‐Alfvénic outflow jet that was carried by magnetized electrons. Intense electrostatic lower hybrid drift waves were localized in the current sheet center and were probably driven by the super‐Alfvénic electron jet, the velocity of which was approximately equal to the diamagnetic drift of demagnetized ions. Our observations suggest that the guide field significantly modified the structures (Hall electromagnetic fields and current system) and wave properties in the IDR.

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Magnetospheric Multiscale Observations of the Electron Diffusion Region of Large Guide Field Magnetic Reconnection

Cited by 77 publications

References 31 publications

MMS Observation of Asymmetric Reconnection Supported by 3‐D Electron Pressure Divergence

MMS Observation of Asymmetric Reconnection Supported by 3‐D Electron Pressure Divergence

Observations of a Kinetic‐Scale Magnetic Hole in a Reconnection Diffusion Region

Magnetospheric Multiscale Observations of an Ion Diffusion Region With Large Guide Field at the Magnetopause: Current System, Electron Heating, and Plasma Waves

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