Formation and Reconnection of Electron Scale Current Layers in the Turbulent Outflows of a Primary Reconnection Site

Lapenta, Giovanni; Goldman, M. V.; Newman, D. L.; Eriksson, S.

doi:10.3847/1538-4357/ac98bc

Cited by 3 publications

(4 citation statements)

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“…However, one should note that this situation is typically limited to local diffusion regions, where the dynamics developed along another dimension may be at an early stage, and hence its effect can be assumed to be negligible (Hesse et al 2016). When being extended to a large-scale context, particularly energy transport by out-propagating reconnection jets and fronts, enough time and space would be accessible to the third-dimension dynamics, such as kinetic instabilities (Lapenta et al 2022). Note that even in the 2D Figure 4.…”

Section: Discussionmentioning

confidence: 99%

“…The two-scale reconnection diagram has been successful in explaining many physical features seen in laboratory experiments and spacecraft observations and is widely accepted as a standard physical model (Pritchett 2001). Nevertheless, three-dimensional (3D) effects have been suggested to play a potential role in altering reconnection physics, such as particle acceleration and turbulence generation (Daughton et al 2011;Dahlin et al 2017;Lapenta et al 2022).…”

Section: Introductionmentioning

confidence: 99%

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Observations of Electron Secondary Reconnection in Magnetic Reconnection Front

Liu,

Cao,

Xing

et al. 2024

ApJ

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Magnetic reconnection, a fundamental plasma process transforming magnetic field energy into particle energy, is ubiquitous in space and responsible for many explosive phenomena, such as solar flares and gamma-ray bursts. Recent numerical theories have predicted that reconnection fronts far from the primary reconnection region can host secondary reconnection in three-dimensional scenarios, different from the conventional two-dimensional diagram where only one X-line stands to sustain reconnection. In this study, we provide direct observational evidence for ongoing secondary reconnection in the reconnection front via the unprecedentedly high-cadence data from NASA’s MMS mission. The secondary reconnection is identified by the presence of an X-line, a super-Alfvénic electron jet, and nonideal energy dissipation. Different from the primary ion–electron reconnection, the secondary reconnection is electron-only, with its X-line quasi-perpendicular to the primary X-line. Hence reconnection, when evolving from local to global scales, becomes essentially three-dimensional with different patterns developed. These results provide crucial insights into understanding cross-scale energy transport driven by reconnection in space plasmas.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Observations of Electron Secondary Reconnection in Magnetic Reconnection Front

Liu,

Cao,

Xing

et al. 2024

ApJ

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“…It is not obvious, however, whether MVAB or hybrid-LMN is the preferred system in general near the Sun, where the L-direction of CSs may be characterized by a preferential radial component of the magnetic field, such as one associated with the HCS. In this scenario, the Parker Solar Probe will traverse a substantial distance along a possibly turbulent reconnection exhaust region (Lapenta et al 2022) before making a complete crossing of a CS along its normal direction. Highly oblique CS trajectories (V Lcs ?…”

Section: Coordinate System Analysis: Mvab and Hybrid-lmnmentioning

confidence: 99%

Parker Solar Probe Observations of Magnetic Reconnection Exhausts in Quiescent Plasmas near the Sun

Eriksson,

Swisdak,

Mallet

et al. 2024

ApJ

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Parker Solar Probe observations are analyzed for the presence of reconnection exhausts across current sheets (CSs) within R < 0.26 au during encounters 4–11. Exhausts are observed with nearly equal probability at all radial distances with a preference for quiescent Tp < 0.80 MK plasmas typical of a slow-wind regime. High Tp > 0.80 MK plasmas of a fast wind characterized by significant transverse fluctuations rarely support exhausts irrespective of the CS width. Exhaust observations demonstrate the presence of local temperature gradients across several CSs with a higher-Tp plasma on locally closed fields and a lower-Tp plasma on locally open field lines for an interchange-type reconnection. A CS geometry analysis directly supports the property that X-lines bisect the magnetic field rotation θ-angle, whether the fields and plasmas are asymmetric or not, to maximize reconnection rates and available magnetic energy. The CS normal width d cs distributions suggest that a multiscale reconnection process through nested layers of bifurcated CSs may be responsible for observed power-law distributions beyond the median d cs ∼ 1000 km with an exponential d cs distribution present for ion kinetic dissipation scales below this median. Magnetic field shear θ-angles are essentially identical at R < 0.26 and 1 au with medians at θ ∼ 55° near the Sun and θ ∼ 65° at 1 au. In contrast, the tangential flow shear distributions are different near and far from the Sun. A bimodal flow shear angle distribution is present near the Sun with strong shear flow magnitudes. This distribution is modified with radial distance toward a relatively flat distribution of weaker flow shear magnitudes.

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“…PIC simulation has particle noise at scales under the Debye length, which can lead to a large overestimation of the null points. To avoid this numerical issue, we use a clustering algorithm called density-based spatial clustering of applications with noise(Ester 1996;Lapenta et al 2022). If there is a number of X points (or O points) with a distance of less than 0.5 d e0 (where d e0 is the electron inertial length in the upstream region…”

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confidence: 99%

Properties of Electron-scale Magnetic Reconnection at a Quasi-perpendicular Shock

Guo,

Lu,

et al. 2023

ApJ

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Recent spacecraft observations have shown that magnetic reconnection occurs commonly in turbulent environments at shocks. At quasi-perpendicular shocks, magnetic field lines are bent by the back-streaming reflected ions, which form a current sheet in the foot region, and then electron-scale reconnection occurs when the current sheet is fragmented at the shock front. Here we study magnetic reconnection at a quasi-perpendicular shock by using a two-dimensional particle-in-cell simulation. Collective properties of the reconnection sites from the shock transition to the downstream region are analyzed by adopting a statistical approach to the simulation data. Reconnecting current sheets are found to be densely distributed near the shock front, with a reconnection electric field larger than those in the downstream region. By tracing a reconnection site from its formation until it is convected downstream, we show the reconnection proceeds intermittently after an active stage near the shock front. Our tracing further shows that, in addition to being originated from the shock front, reconnection in the downstream region can also occur locally, driven by turbulent flows therein. The results help us better understand the evolution of electron-scale reconnection at a perpendicular shock.

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Formation and Reconnection of Electron Scale Current Layers in the Turbulent Outflows of a Primary Reconnection Site

Cited by 3 publications

References 50 publications

Observations of Electron Secondary Reconnection in Magnetic Reconnection Front

Observations of Electron Secondary Reconnection in Magnetic Reconnection Front

Parker Solar Probe Observations of Magnetic Reconnection Exhausts in Quiescent Plasmas near the Sun

Properties of Electron-scale Magnetic Reconnection at a Quasi-perpendicular Shock

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