Revealing the sub-structures of the magnetic reconnection separatrix via particle-in-cell simulation

Zhou, Mingyue; Deng, Xiaohua; Pang, Y.; Huang, Suming; Yuan, Zhigang; Li, H. M.; Xu, Xiaokang; Wang, Y. H.; Yao, Ming; Wang, D. D.

doi:10.1063/1.4739283

Cited by 22 publications

(27 citation statements)

References 24 publications

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“…The nonzero J·E′ means the existence of nonideal electric field around the separatrices, which has been reported in particle simulation (Zhou et al, ). Comparing Figures h and i, we find that J·E and J·E′ were nearly the same, which implies that most of the magnetic energy went to heat instead of bulk accelerating the plasma.…”

Section: Novel Properties Of the Idrmentioning

confidence: 69%

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 Idrmentioning

confidence: 69%

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

et al. 2019

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“…Magnetic and electric fields, and plasma moments, such as plasma density and bulk velocity, have been averaged in a ±0.2 ω ci −1 window in order to reduce high‐frequency noise [ Zhou et al ., ]. For convenience and symmetry reason, we show only the results of the upper current sheet.…”

Section: Simulation Resultsmentioning

confidence: 99%

Plasma physics of magnetic island coalescence during magnetic reconnection

et al. 2014

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A large-scale two-dimensional electromagnetic particle-in-cell simulation was employed to study the magnetic island coalescence/merging process during magnetic reconnection with guide field. The merged island after coalescence is characterized by strong core field and plasma density dip at the island center. We found that the core field enhancement is caused by the out-of-plane magnetic field pileup, as well as the field line twisting due to Hall effect. There is an in-plane electric current loop, which is mainly carried by electrons, circumventing the enhanced core field region. Total force points away or tangentially to the surface of density dip within the merged island, which prevents electrons from higher-density region entering the lower density region between two merging islands. This is contrary to the force in the secondary island, inside which the total force points toward the island center and constrains plasma there. The coalescence process involves a reconnection at the merging sheet between two islands. Electron frozen-in condition is violated locally along the merging sheet. It is contributed by both the divergence of electron pressure tensor and electron inertial. Energy dissipation is concentrated on the merging line during coalescence, while a train of dynamo (j′ · E′ < 0) and dissipation (j′ · E′ > 0) regions are distributed along the merging sheet after coalescence. Electrons and ions within the density dip at the island center are accelerated antiparallel to the ambient magnetic field, i.e., along the out-of-plane direction. The resultant distribution can excite the Buneman instability and two-streaming instability, which probably account for the electrostatic solitary waves observed by satellite.

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“…A small system size flux perturbation is added initially to boost the system entering the nonlinear stage. Details of this model have been discussed in Zhou et al (2012b).…”

Section: Simulation Resultsmentioning

confidence: 99%

Tripolar electric field Structure in guide field magnetic reconnection

Huang

Zhou

et al. 2018

Ann. Geophys.

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Abstract. It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (B g ). Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B 0 , the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed.

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Revealing the sub-structures of the magnetic reconnection separatrix via particle-in-cell simulation

Cited by 22 publications

References 24 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

Plasma physics of magnetic island coalescence during magnetic reconnection

Tripolar electric field Structure in guide field magnetic reconnection

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