Electron‐Scale Reconnection in Three‐Dimensional Shock Turbulence

Ng, Jonathan; Chen, L. -J.; Bessho, Naoki; Shuster, J. R.; Burkholder, Brandon; Yoo, Jongsoo

doi:10.1029/2022gl099544

Cited by 17 publications

(13 citation statements)

References 35 publications

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“…Panel (c) of Figure 5 shows the velocity of MFT (V MFT ), which has been known to increase sharply around the x-line and decrease rapidly moving away from the x-line (Li et al 2021(Li et al , 2023Ng et al 2022;Qi et al 2022). In panel (c), all four-spacecraft measure greatly enhanced V MFT , consistent with being an EDR crossing.…”

Section: In-plane Magnetic Reconnection Featuresmentioning

confidence: 83%

“…E is the electric field, V e is the electron velocity, and B is the magnetic field) (Burch et al 2018;Pritchard et al 2019;Hesse & Cassak 2020;Lu et al 2020). In addition, the velocity of the magnetic flux transport (U ψ ) has recently been proven to be a localized indicator of active reconnection (Li et al 2021;Ng et al 2022;Qi et al 2022).…”

Section: Introductionmentioning

confidence: 99%

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The Nonorthogonal X-line in a Small Guide-field Reconnection Event in the Magnetotail

Qi¹,

Ergun²,

Pathak³

et al. 2023

ApJ

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Magnetic reconnection is a fundamental plasma process that has been studied with analytical theory, numerical simulations, in situ observations, and laboratory experiments for decades. The models that have been established to describe magnetic reconnection often assume a reconnection plane normal to the current sheet in which an antiparallel magnetic field annihilates. The annihilation points, also known as the X-points, form an x-line, which is believed to be perpendicular to the reconnection plane. Recently, a new study using Magnetospheric Multiscale mission observations has challenged our understanding of magnetic reconnection by providing evidence that the x-line is not necessarily orthogonal to the reconnection plane. In this study we report a second nonorthogonal x-line event with similar features as that in the previous case study, supporting that the sheared x-line phenomenon is not an aberrant event. We employ a detailed directional derivative analysis to identify the x-line direction and show that the in-plane reconnection characteristics are well maintained even with a nonorthogonal x-line. In addition, we find the x-line tends to follow the magnetic field on one side of the current sheet, which suggests an asymmetry across the current sheet. We discuss the possibility that the nonorthogonal x-line arises from an interplay between the two aspects of reconnection: the macroscopic magnetic field topology and microscopic particle kinetics.

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Section: In-plane Magnetic Reconnection Featuresmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

The Nonorthogonal X-line in a Small Guide-field Reconnection Event in the Magnetotail

Qi¹,

Ergun²,

Pathak³

et al. 2023

ApJ

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“…Full PIC and hybrid PIC simulations (Karimabadi et al 2014;Matsumoto et al 2015;Bohdan et al 2017Bohdan et al , 2020Gingell et al 2017Gingell et al , 2023Bessho et al 2019Bessho et al , 2020Bessho et al , 2022Lu et al 2021;Ng et al 2022) show magnetic reconnection in the shock-driven turbulence, and ion-coupled reconnection can also occur where both ion and electron jets are produced. Ioncoupled reconnection has been observed by MMS (Yordanova et al 2016;Vörös et al 2017;Wang et al 2019;Stawarz et al 2022) in the magnetosheath and the transition region of the Earth's bow shock.…”

Section: Introductionmentioning

confidence: 99%

Electron Acceleration and Heating during Magnetic Reconnection in the Earth's Quasi-parallel Bow Shock

Bessho,

Chen,

Hesse

et al. 2023

ApJ

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We perform a 2.5-dimensional particle-in-cell simulation of a quasi-parallel shock, using parameters for the Earth’s bow shock, to examine electron acceleration and heating due to magnetic reconnection. The shock transition region evolves from the ion-coupled reconnection dominant stage to the electron-only reconnection dominant stage, as time elapses. The electron temperature enhances locally in each reconnection site, and ion-scale magnetic islands generated by ion-coupled reconnection show the most significant enhancement of the electron temperature. The electron energy spectrum shows a power law, with a power-law index around 6. We perform electron trajectory tracing to understand how they are energized. Some electrons interact with multiple electron-only reconnection sties, and Fermi acceleration occurs during multiple reflections. Electrons trapped in ion-scale magnetic islands can be accelerated in another mechanism. Islands move in the shock transition region, and electrons can obtain larger energy from the in-plane electric field than the electric potential in those islands. These newly found energization mechanisms in magnetic islands in the shock can accelerate electrons to energies larger than the achievable energies by the conventional energization due to the parallel electric field and shock drift acceleration. This study based on the selected particle analysis indicates that the maximum energy in the nonthermal electrons is achieved through acceleration in ion-scale islands, and electron-only reconnection accounts for no more than half of the maximum energy, as the lifetime of sub-ion-scale islands produced by electron-only reconnection is several times shorter than that of ion-scale islands.

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“…The MFT method has been demonstrated to accurately identify reconnection in 2D gyrokinetic turbulence [39] and 3D shock turbulence [52] simulations. Recent MMS observations have further demonstrated the accuracy of MFT statistically, having directly measured MFT signatures for active reconnection throughout Earth's magnetosphere [47].…”

mentioning

confidence: 99%

“…With applicability to both simulations and in situ observations [39,47,52], the MFT method opens opportunities for studying reconnection in turbulence. Although here we have identified extended reconnection in kinetic turbulence, future work could explore how extended X-lines contribute to plasma heating at kinetic scales, where energy is dissipated, how reconnection spatially distributes in electron-scale turbulence, and new properties of reconnection in turbulent systems in space, laboratory, and astrophysical plasmas.…”

mentioning

confidence: 99%

Extended magnetic reconnection in kinetic plasma turbulence

Li¹,

Liu²,

Yi³

et al. 2023

Preprint

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Magnetic reconnection and plasma turbulence are ubiquitous processes important for laboratory, space and astrophysical plasmas. Reconnection has been suggested to play an important role in the energetics and dynamics of turbulence by observations, simulations and theory for two decades. The fundamental properties of reconnection at kinetic scales, essential to understanding reconnection in turbulence, remain largely unknown at present. Here we present an application of the magnetic flux transport method that can accurately identify reconnection in turbulence to a three-dimensional simulation. Contrary to ideas that reconnection in turbulence would be patchy and unpredictable, highly extended reconnection X-lines, on the same order of magnitude as the system size, form at kinetic scales. Extended X-lines develop through bi-directional reconnection spreading, and satisfy critical balance characteristic of turbulence. This presents a new picture of fundamentally extended reconnection in kinetic-scale turbulence.

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Electron‐Scale Reconnection in Three‐Dimensional Shock Turbulence

Cited by 17 publications

References 35 publications

The Nonorthogonal X-line in a Small Guide-field Reconnection Event in the Magnetotail

The Nonorthogonal X-line in a Small Guide-field Reconnection Event in the Magnetotail

Electron Acceleration and Heating during Magnetic Reconnection in the Earth's Quasi-parallel Bow Shock

Extended magnetic reconnection in kinetic plasma turbulence

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