Turbulence-driven magnetic reconnection and the magnetic correlation length: Observations from Magnetospheric Multiscale in Earth's magnetosheath

The Earth&#8217;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 &#8220;electron-only&#8221; 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&#8217;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-Alfv&#233;nic ion jets and super- Alfv&#233;nic 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.

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The effect of plasmaspheric material on magnetopause reconnection

10.5194/egusphere-egu2020-9760 ◽

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

The Earth&#8217;s plasmasphere contains cold (~eV energy) dense (>100 cm-3) plasma of ionospheric origin. The primary ion constituents of the plasmasphere are H+&#160;and He+, and a lower concentration of O+. 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+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.

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Electrons Thrown Off Course in Near-Earth Magnetic Reconnection

Eos ◽

10.1029/2016eo051175 ◽

2016 ◽

Vol 97 ◽

Author(s):

Aleida Higginson

Keyword(s):

Magnetic Reconnection ◽

Magnetospheric Multiscale

NASA Magnetospheric Multiscale (MMS) mission detects energy differences in electrons scattered by magnetic reconnection.

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

Physical Review Letters ◽

10.1103/physrevlett.117.015001 ◽

2016 ◽

Vol 117 (1) ◽

Cited By ~ 43

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

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Secondary Magnetic Reconnection at Earth’s Flank Magnetopause

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2021.740560 ◽

2021 ◽

Vol 8 ◽

Author(s):

B. B. Tang ◽

W. Y. Li ◽

C. Wang ◽

Yu. V. Khotyaintsev ◽

D. B. Graham ◽

...

Keyword(s):

Solar Wind ◽

Magnetic Reconnection ◽

Open Field ◽

Global Scale ◽

Diffusion Region ◽

Magnetic Shear ◽

Magnetospheric Multiscale ◽

Field Lines ◽

Secondary Ion ◽

Magnetospheric Field

We report local secondary magnetic reconnection at Earth’s flank magnetopause by using the Magnetospheric Multiscale observations. This reconnection is found at the magnetopause boundary with a large magnetic shear between closed magnetospheric field lines and the open field lines generated by the primary magnetopause reconnection at large scales. Evidence of this secondary reconnection are presented, which include a secondary ion jet and the encounter of the electron diffusion region. Thus the observed secondary reconnection indicates a cross-scale process from a global scale to an electron scale. As the aurora brightening is also observed at the morning ionosphere, the present secondary reconnection suggests a new pathway for the entry of the solar wind into geospace, providing an important modification to the classic Dungey cycle.

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Magnetic Nanoparticle Aggregation States in Ag100-xFex Cosputtered Granular Films Investigated by Magnetic and Magnetotransport Measurements

MRS Proceedings ◽

10.1557/proc-877-s5.4 ◽

2005 ◽

Vol 877 ◽

Cited By ~ 1

Author(s):

Paolo Allia ◽

Federica Celegato ◽

Marco Coisson ◽

Paola Tiberto ◽

Franco Vinai ◽

...

Keyword(s):

Free Path ◽

Temperature Interval ◽

Correlation Length ◽

Magnetic Nanoparticle ◽

Magnetic Moments ◽

Mean Free Path ◽

Nanoparticle Aggregation ◽

Competing Interactions ◽

Granular Films ◽

Magnetic Correlation

AbstractMagnetoresistance and.magnetization measurements have been performed on nanogranular, cosputtered Ag100-xFex films (x= 10 to 30) in the 4 K – 300 K temperature interval. The analysis reveals that the films with x ≤ 14 are interacting superparamagnets, characterized by a magnetic correlation length of the order of the electronic mean free path λ. Films with x ≥ 26 behave as concentrated magnets with strong competing interactions among magnetic moments (frustrated ferromagnets) and magnetic correlation length much larger than λ.

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Magnetic Curvature Analysis on Reconnection Related Structures at Earth’s Magnetopause

10.5194/egusphere-egu2020-3764 ◽

2020 ◽

Author(s):

Yi Qi ◽

Christopher T. Russell ◽

Robert J. Strangeway ◽

Yingdong Jia ◽

Roy B. Torbert ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Magnetic Reconnection ◽

Solar Wind Plasma ◽

Radius Of Curvature ◽

Plasma Properties ◽

Magnetospheric Multiscale ◽

Reconnection Site ◽

Field Lines ◽

The Magnetic Field

Magnetic reconnection is a mechanism that allows rapid and explosive energy transfer from the magnetic field to the plasma. The magnetopause is the interface between the shocked solar wind plasma and Earth&#8217;s magnetosphere. Reconnection enables the transport of momentum from the solar wind into Earth&#8217;s magnetosphere. Because of its importance in this regard, magnetic reconnection has been extensively studied in the past and is the primary goal of the ongoing Magnetospheric Multiscale (MMS) mission. During magnetic reconnection, the originally anti-parallel fields annihilate and reconnect in a thinned current sheet. In the vicinity of a reconnection site, a prominently increased curvature of the magnetic field (and smaller radius of curvature) marks the region where the particles start to deviate from their regular gyro-motion and become available for energy conversion. Before MMS, there were no closely separated multi-spacecraft missions capable of resolving these micro-scale curvature features, nor examining particle dynamics with sufficiently fast cadence.In this study, we use measurements from the four MMS spacecraft to determine the curvature of the field lines and the plasma properties near the reconnection site. We use this method to study FTEs (flux ropes) on the magnetopause, and the interaction between co-existing FTEs. Our study not only improves our understanding of magnetic reconnection, but also resolves the relationship between FTEs and structures on the magnetopause.

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Observations of Plasma Waves in the Multiple X-line Reconnection at the Magnetopause

10.5194/egusphere-egu2020-8731 ◽

2020 ◽

Author(s):

Zhihong Zhong ◽

Daniel B. Graham ◽

Yuri V. Khotyaintsev ◽

Meng Zhou ◽

Rongxin Tang ◽

...

Keyword(s):

Magnetic Reconnection ◽

Plasma Waves ◽

Distribution Functions ◽

Electron Velocity ◽

Electron Velocity Distribution ◽

Loss Cone ◽

Electrostatic Waves ◽

Magnetospheric Multiscale ◽

Low Energies ◽

Velocity Distribution Functions

Plasma waves are one of the important products of the magnetic reconnection process. &#160;Plasma waves can produce particle heating, diffusion, and anomalous effects, which can potentially affect magnetic reconnection. We investigate the evolution and properties of plasma waves during a multiple X-line reconnection event at the magnetopause using measurements from the Magnetospheric Multiscale (MMS) mission. Both whistler waves and large-amplitude electrostatic waves were observed around the reconnecting current sheet. In these regions, the electron velocity distribution functions consist of a combination of a cold beam at low energies with an anisotropic population or a loss-cone at high energies. The electrostatic waves corresponded to regions where the cold beams are accelerated, while the whistlers corresponded to regions with significant anisotropies or loss cones. When the cold beams were accelerated to higher energies, the whistlers disappeared since the anisotropy or loss-cone distributions became less apparent. These results present the detailed evolution of the plasma waves reflecting the electron dynamics during magnetic reconnection.

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