Observation of non-gyrotropic electron distribution across the electron diffusion region in the magnetotail reconnection

2020 ◽  
Author(s):  
Xinmin Li ◽  
Quanming Lu
Keyword(s):  
Electric Field ◽  
Energy Range ◽  
Electron Distribution ◽  
Distribution Functions ◽  
Diffusion Region ◽  
Electron Diffusion ◽  
Vertical Distance ◽  
Magnetospheric Multiscale ◽  
Magnetotail Reconnection ◽  
First Time

<p>Using measurements by the Magnetospheric Multiscale (MMS) spacecraft in the magnetotail, we studied electron distribution functions across an electron diffusion region. The dependence of the non-gyrotropic distribution on the energy and vertical distance from the EDR mid-plane was revealed for the first time. The non-gyrotropic distribution was observed everywhere except for an extremely narrow layer right at the EDR mid-plane. The energy of the non-gyrotropic distribution increased with growth of the vertical distance from the mid-plane. For the electrons within certain energy range, they exhibited the non-gyrotropic distribution at the distance further away from the mid-plane than that expected from the meandering motion. The correlation between the crescent-shaped distribution with multiple stripes and the large Hall electric field was established. It appears that the measured non-gyrotropic distribution and the crescent-shaped distribution were caused by the meandering motion and the Hall electric field together.</p>

Nonideal Electric Field Observed in the Separatrix Region of a Magnetotail Reconnection Event

2020 ◽  
Author(s):  
Xiancai Yu ◽  
Rongsheng Wang ◽  
Quanming Lu
Keyword(s):  
Energy Dissipation ◽  
Electric Field ◽  
Current Sheet ◽  
Thermal Energy ◽  
Electrostatic Potential ◽  
Electron Distribution ◽  
Diffusion Region ◽  
Pressure Tensor ◽  
Magnetospheric Multiscale ◽  
Magnetotail Reconnection

<p>The microphysics in the separatrix region (SR) plays an important role for the energy conversion in reconnection. Based on the Magnetospheric Multiscale observations in the magnetotail, we present a complete crossing of the current sheet with ongoing magnetic reconnection. The field‐aligned inflowing electrons were observed in both separatrix regions (SRs) and their energy extended up to several times of the thermal energy. Along the SR, a net parallel electrostatic potential was estimated and could be the reason for the inflowing electron streaming. In the northern SR, the electron frozen‐in condition was violated and nonideal electric field was inferred to be caused by the gradient of the electron pressure tensor. The nongyrotropic electron distribution and significant energy dissipation were observed at the same region. The observations indicate that the inner electron diffusion region can extend along the separatrices or some electron‐scale instability can be destabilized in the SR. </p>

Observation of Nongyrotropic Electron Distribution Across the Electron Diffusion Region in the Magnetotail Reconnection

2019 ◽  
Vol 46 (24) ◽  
pp. 14263-14273 ◽  
Author(s):  
Xinmin Li ◽  
Rongsheng Wang ◽  
Quanming Lu ◽  
Kyoung‐Joo Hwang ◽  
Qiugang Zong ◽  
...  
Keyword(s):  
Electron Distribution ◽  
Diffusion Region ◽  
Electron Diffusion ◽  
Magnetotail Reconnection

CCMC Modeling of Magnetic Reconnection in Electron Diffusion Region Events

2017 ◽  
Vol 13 (S335) ◽  
pp. 142-146
Author(s):  
Patricia H. Reiff ◽  
James M. Webster ◽  
Antoun G. Daou ◽  
Andrew Marshall ◽  
Stanislav Y. Sazykin ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Diffusion Region ◽  
Electron Diffusion ◽  
Reconnection Process ◽  
Magnetospheric Multiscale ◽  
Magnetospheric Multiscale Mission ◽  
First Time

AbstractWe use numerical simulations from the Community Coordinated Modeling Center to provide, for the first time, a coherent temporal description of the magnetic reconnection process of two dayside Electron Diffusion Regions (EDRs) identified in Magnetospheric Multiscale Mission data. The model places the MMS spacecraft near the separator line in these most intense and long-lived events. A listing of 31 dayside EDRs identified by the authors is provided to encourage collaboration in analysis of these unique encounters.

scholarly journals Spatial dimensions of the electron diffusion region in anti-parallel magnetic reconnection

2016 ◽  
Vol 34 (3) ◽  
pp. 357-367 ◽  
Author(s):  
Takuma Nakamura ◽  
Rumi Nakamura ◽  
Hiroshi Haseagwa
Keyword(s):  
Electric Field ◽  
Magnetic Reconnection ◽  
Real Space ◽  
Diffusion Region ◽  
Electron Mass ◽  
Plasma Parameters ◽  
Electron Diffusion ◽  
Background Density ◽  
Spatial Dimensions ◽  
Inner Region

Abstract. Spatial dimensions of the detailed structures of the electron diffusion region in anti-parallel magnetic reconnection were analyzed based on two-dimensional fully kinetic particle-in-cell simulations. The electron diffusion region in this study is defined as the region where the positive reconnection electric field is sustained by the electron inertial and non-gyrotropic pressure components. Past kinetic studies demonstrated that the dimensions of the whole electron diffusion region and the inner non-gyrotropic region are scaled by the electron inertial length de and the width of the electron meandering motion, respectively. In this study, we successfully obtained more precise scalings of the dimensions of these two regions than the previous studies by performing simulations with sufficiently small grid spacing (1∕16–1∕8 de) and a sufficient number of particles (800 particles cell−1 on average) under different conditions changing the ion-to-electron mass ratio, the background density and the electron βe (temperature). The obtained scalings are adequately supported by some theories considering spatial variations of field and plasma parameters within the diffusion region. In the reconnection inflow direction, the dimensions of both regions are proportional to de based on the background density. Both dimensions also depend on βe based on the background values, but the dependence in the inner region ( ∼ 0.375th power) is larger than the whole region (0.125th power) reflecting the orbits of meandering and accelerated electrons within the inner region. In the outflow direction, almost only the non-gyrotropic component sustains the positive reconnection electric field. The dimension of this single-scale diffusion region is proportional to the ion-electron hybrid inertial length (dide)1∕2 based on the background density and weakly depends on the background βe with the 0.25th power. These firm scalings allow us to predict observable dimensions in real space which are indeed in reasonable agreement with past in situ spacecraft observations in the Earth's magnetotail and have important implications for future observations with higher resolutions such as the NASA Magnetospheric Multiscale (MMS) mission.

Plasma Currents and Electron Distribution Functions under a dc Electric Field of Arbitrary Strength

2008 ◽  
Vol 100 (18) ◽  
Author(s):  
S. M. Weng ◽  
Z. M. Sheng ◽  
M. Q. He ◽  
J. Zhang ◽  
P. A. Norreys ◽  
...  
Keyword(s):  
Electric Field ◽  
Electron Distribution ◽  
Distribution Functions ◽  
Arbitrary Strength ◽  
Dc Electric Field

Reconstruction of the electron diffusion region observed by the Magnetospheric Multiscale spacecraft: First results

2017 ◽  
Vol 44 (10) ◽  
pp. 4566-4574 ◽  
Author(s):  
H. Hasegawa ◽  
B. U. Ö. Sonnerup ◽  
R. E. Denton ◽  
T.-D. Phan ◽  
T. K. M. Nakamura ◽  
...  
Keyword(s):  
Diffusion Region ◽  
Electron Diffusion ◽  
Magnetospheric Multiscale ◽  
First Results

How does dissipation work in the electron diffusion region of asymmetric magnetic reconnection

2020 ◽  
Author(s):  
Michael Hesse ◽  
Cecilia Norgren ◽  
Paul Tenfjord ◽  
James Burch ◽  
Yi-Hsin Liu ◽  
...  
Keyword(s):  
Electric Field ◽  
Magnetic Reconnection ◽  
Stagnation Point ◽  
Electric Fields ◽  
Current Density ◽  
Electron Flow ◽  
Diffusion Region ◽  
Density Maximum ◽  
Density Peak ◽  
Electron Diffusion

<p>At some level, magnetic reconnection functions by means of a balance between current dissipation, and current maintenance due to the reconnection electric field. While this dissipation is well understood process in symmetric magnetic reconnection, the way nonideal electric fields interact with the current density in asymmetric reconnection is still unclear. In symmetric reconnection, the current density maximum, the X point location, and the nonideal electric field determined by the divergence of the electron pressure tensor usually coincide. In asymmetric reconnection, however, the electric field at the X point can be partly provided by bulk inertia terms, implying that the X point cannot be the dominant location of dissipation. On the other hand, we know that the nongyrotropic pressure-based electric field must dominate at the stagnation point of the in-plane electron flow, and that electron distributions here feature crescents. The further fact that the current density peak is shifted off the position of the X point indicates that there may be a relation between this current density enhancement, the location of the stagnation point, and the electron nongyrotropies. In this presentation we report on further progress investigating the physics of the electron diffusion region in asymmetric reconnection with a focus on how to explain the dissipation operating under these conditions. </p>

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