scholarly journals MMS Observation of the Hall Field in an Asymmetric Magnetic Reconnection with Guide Field

2021 ◽  
Vol 922 (2) ◽  
pp. 96
Author(s):  
S. Y. Tang ◽  
Y. C. Zhang ◽  
L. Dai ◽  
T. Chen ◽  
C. Wang
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Comprehensive Description ◽  
Guide Field ◽  
The Earth ◽  
Magnetospheric Multiscale ◽  
Out Of Plane ◽  
Magnetospheric Multiscale Mission ◽  
Insight Into ◽  
Study Offer

Abstract In this paper, we investigate the structure of out-of-plane magnetic field in the reconnection event observed by Magnetospheric Multiscale Mission at the magnetopause of the Earth magnetosphere on 2015 October 21. We find that the perturbation of out-of-plane magnetic field in this event is different from previous observations of the quadrupolar Hall magnetic field. The distinct out-of-plane magnetic field is interpreted as a part of the hexapolar Hall magnetic field obtained in a recent simulation of asymmetric reconnection with the guide field. This is significant evidence of hexapolar Hall magnetic field in collisionless magnetic reconnection from the observations in the magnetosphere. High-resolution measurements of particle and field are used to provide a comprehensive description of the features of the hexapolar Hall magnetic field. The results from this study offer an insight into the Hall effect in collisionless magnetic reconnection.

The effect of plasmaspheric material on magnetopause reconnection

2020 ◽  
Author(s):  
Stephen Fuselier ◽  
Stein Haaland ◽  
Paul Tenfjord ◽  
David Malaspina ◽  
James Burch ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Magnetic Reconnection ◽  
Plasma Wave ◽  
Outer Part ◽  
Field Measurements ◽  
Ion Composition ◽  
The Earth ◽  
Magnetospheric Multiscale ◽  
Magnetic Field Measurements

<p>The Earth’s plasmasphere contains cold (~eV energy) dense (>100 cm<sup>-3</sup>) plasma of ionospheric origin. The primary ion constituents of the plasmasphere are H<sup>+ </sup>and He<sup>+</sup>, and a lower concentration of O<sup>+</sup>. The outer part of the plasmasphere, especially on the duskside of the Earth, drains away into the dayside outer magnetosphere when geomagnetic activity increases. Because of its high density and low temperature, this plasma has the potential to modify magnetic reconnection at the magnetopause. To investigate the effect of plasmaspheric material at the magnetopause, Magnetospheric Multiscale (MMS) data are surveyed to identify magnetopause crossings with the highest He<sup>+</sup>densities. Plasma wave, ion, and ion composition data are used to determine densities and mass densities of this plasmaspheric material and the magnetosheath plasma adjacent to the magnetopause. These measurements are combined with magnetic field measurements to determine how the highest density plasmaspheric material in the MMS era may affect reconnection at the magnetopause.</p>

Energy Conversion in the Electron Stagnation Region of Magnetopause Reconnection

2020 ◽  
Author(s):  
James Burch ◽  
James Webster ◽  
Kristina Pritchard ◽  
Kevin Genestreti ◽  
Michael Hesse ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energy Conversion ◽  
Closed Field ◽  
Stagnation Region ◽  
Strong Electron ◽  
The Earth ◽  
Background Magnetic Field ◽  
Out Of Plane ◽  
Uniform Background ◽  
Field Lines

<p>For reconnection at the Earth’s day side, which is asymmetric, the main energy conversion occurs on closed field lines in the electron stagnation region. Energy conversion, as measured by <strong>J</strong>⦁<strong>E</strong>, occurs where out-of-plane electric field components are embedded within larger regions of out-of-plane current, which is carried by strong electron flows in the M direction of the LMN coordinate system. Bracketing these energy conversion sites are electron jet reversals (along L and -L) and converging  electron flows (along N and -N). These electron flows are like those that surround reconnection X lines, however, in these cases they occur completely within closed field lines. The question then is what, if anything, this energy conversion has to do with local reconnection of magnetic field lines. This paper reports on a study of two events observed by MMS on December 29, 2016 and April 15, 2018. The electron inflows have velocities between 0.05 V<sub>eA</sub> and 0.1 V<sub>eA</sub>, (V<sub>eA</sub> = electron Alfvén speed), which are consistent with predicted reconnection rates. Laboratory measurements and 3D simulation results offer some clues about how reconnecting current sheets can evolve in a uniform background magnetic field.</p>

The Relationship Between Electron-Only Magnetic Reconnection and Turbulence in Earth’s Magnetosheath

2020 ◽  
Author(s):  
Julia E. Stawarz ◽  
Jonathan P. Eastwood ◽  
Tai Phan ◽  
Imogen L. Gingell ◽  
Alfred Mallet ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Power Spectra ◽  
Theoretical Work ◽  
Small Scale ◽  
Current Sheets ◽  
The Earth ◽  
Recent Theoretical Work ◽  
Magnetospheric Multiscale ◽  
Scale Turbulence ◽  
The Relationship

<p>The Earth’s magnetosheath is filled with small-scale current sheets arising from turbulent dynamics in the plasma. Previous observations and simulations have provided evidence that such current sheets can be sites for magnetic reconnection. Recently, observations from the Magnetospheric Multiscale (MMS) mission have revealed that a novel form of “electron-only” reconnection can occur at these small-scale, turbulence-driven current sheets, in which ions do not appear to couple to the reconnected magnetic field to form ion jets. The presence of electron-only reconnection may facilitate dissipation of the turbulence, thereby influencing the partition of energy between ions and electrons, and can alter the nonlinear dynamics of the turbulence itself. In this study, we perform a survey of turbulent intervals in the Earth’s magnetosheath as observed by MMS in order to determine how common magnetic reconnection is in the turbulent magnetosheath and how it impacts the small-scale turbulent dynamics. The magnetic correlation length, which dictates the length of the turbulent current sheets, is short enough in most of the examined intervals for reconnection with reduced or absent ion jets to occur. Magnetic reconnection is found to be a common feature within these intervals, with a significant fraction of reconnecting current sheets showing evidence of sub-Alfvénic ion jets and super- Alfvénic electron jets, consistent with electron-only reconnection. Moreover, a subset of the intervals exhibit changes in the behavior of the small-scale magnetic power spectra, which may be related to the reconnecting current sheets. The results of the survey are compared with recent theoretical work on electron-only reconnection in turbulent plasmas.</p>

scholarly journals Evolution of magnetic helicity under kinetic magnetic reconnection: Part II B ≠ 0 reconnection

2002 ◽  
Vol 9 (2) ◽  
pp. 139-147 ◽  
Author(s):  
T. Wiegelmann ◽  
J. Büchner
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Hall Current ◽  
Neutral Line ◽  
Magnetic Helicity ◽  
Perpendicular Magnetic Field ◽  
Guide Field ◽  
Magnetic Neutral Line ◽  
Field Lines ◽  
The Magnetic Field

Abstract. We investigate the evolution of magnetic helicity under kinetic magnetic reconnection in thin current sheets. We use Harris sheet equilibria and superimpose an external magnetic guide field. Consequently, the classical 2D magnetic neutral line becomes a field line here, causing a B ≠ 0 reconnection. While without a guide field, the Hall effect leads to a quadrupolar structure in the perpendicular magnetic field and the helicity density, this effect vanishes in the B ≠ 0 reconnection. The reason is that electrons are magnetized in the guide field and the Hall current does not occur. While a B = 0 reconnection leads just to a bending of the field lines in the reconnection area, thus conserving the helicity, the initial helicity is reduced for a B ≠ 0 reconnection. The helicity reduction is, however, slower than the magnetic field dissipation. The simulations have been carried out by the numerical integration of the Vlasov-equation.

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

2016 ◽  
Vol 117 (1) ◽  
Author(s):  
S. Eriksson ◽  
F. D. Wilder ◽  
R. E. Ergun ◽  
S. J. Schwartz ◽  
P. A. Cassak ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Diffusion Region ◽  
Electron Diffusion ◽  
Guide Field ◽  
Magnetospheric Multiscale

scholarly journals Tripolar electric field Structure in guide field magnetic reconnection

2018 ◽  
Vol 36 (2) ◽  
pp. 373-379 ◽  
Author(s):  
Song Fu ◽  
Shiyong Huang ◽  
Meng Zhou ◽  
Binbin Ni ◽  
Xiaohua Deng
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Magnetic Reconnection ◽  
Electric Fields ◽  
Particle Simulation ◽  
Space Plasma Physics ◽  
Guide Field ◽  
Substantial Modification ◽  
Reconnection Layer ◽  
The Magnetic Field

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 (Bg). Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, 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. Keywords. Space plasma physics (magnetic reconnection)

MMS Observation of Intermittent Energy Dissipation in Magnetic Reconnection Diffusion Region

2021 ◽  
Author(s):  
Xiangcheng Dong ◽  
Malcolm Dunlop ◽  
Tieyan Wang ◽  
Jinsong Zhao ◽  
Huishan Fu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energy Dissipation ◽  
Electric Field ◽  
Comparative Study ◽  
Spatial Effect ◽  
Diffusion Region ◽  
Common Phenomenon ◽  
Magnetospheric Multiscale ◽  
Out Of Plane ◽  
Current Behavior

<p>Magnetospheric Multiscale (MMS) data are used to investigate the energy dissipation in a  reconnection diffusion region at the magnetopause. The four MMS spacecraft were separated by about 10 km such that comparative study between each spacecraft within the diffusion region can be implemented. Similar magnetic field and electric current behavior between each spacecraft indicates the formation of a quasi-homogeneous diffusion region structure. However, we find that the energy dissipation results between each spacecraft are different due to the temporal or spatial effect of the out-of-plane merging electric field (E<sub>M</sub>) during the dissipation region. Our study suggests that the intermittent energy dissipation in the reconnection dissipation region can be a common phenomenon, even under a stable diffusion region structure.</p>

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