Direct evidence of secondary reconnection inside filamentary currents of magnetic flux ropes in magnetic reconnection

2020 ◽  
Author(s):  
Shimou Wang ◽  
Quanming Lu
Keyword(s):  
Energy Dissipation ◽  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Magnetic Energy ◽  
Flux Rope ◽  
Plasma Jets ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Reconnecting Current Sheet

<p>Magnetic reconnection is a fundamental plasma process, by which magnetic energy is explosively released in the current sheet to energize charged particles and to create bi-directional Alfvénic plasma jets. A long-outstanding issue is how the stored magnetic energy is rapidly released in the process. Numerical simulations and observations show that formation and interaction of magnetic flux ropes dominate the evolution of the reconnecting current sheet. Accordingly, most volume of the reconnecting current sheet is occupied by the flux ropes and energy dissipation primarily occurs along their edges via the flux rope coalescence. Here, for the first time, we present in-situ evidence of magnetic reconnection inside the filamentary currents which was driven possibly by electron vortices inside the flux ropes. Our results reveal an important new way for energy dissipation in magnetic reconnection.</p>

scholarly journals Observations of magnetic flux ropes during magnetic reconnection in the Earth's magnetotail

2012 ◽  
Vol 30 (5) ◽  
pp. 761-773 ◽  
Author(s):  
A. L. Borg ◽  
M. G. G. T. Taylor ◽  
J. P. Eastwood
Keyword(s):  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Electron Flux ◽  
Energetic Electron ◽  
Flux Rope ◽  
Clear Correlation ◽  
Particle Measurements ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Show Evidence

Abstract. We present an investigation of magnetic flux ropes observed by the four Cluster spacecraft during periods of magnetic reconnection in the Earth's magnetotail. Using a list of 21 Cluster encounters with the reconnection process in the period 2001–2006 identified in Borg et al. (2012), we present the distribution and characteristics of the flux ropes. We find 27 flux ropes embedded in the reconnection outflows of only 11 of the 21 reconnection encounters. Reconnection processes associated with no flux rope observations were not distinguishable from those where flux ropes were observed. Only 7 of the 27 flux ropes show evidence of enhanced energetic electron flux above 50 keV, and there was no clear signature of the flux rope in the thermal particle measurements. We found no clear correlation between the flux rope core field and the prevailing IMF By direction.

scholarly journals Asymmetry in the current sheet and secondary magnetic flux ropes during guide field magnetic reconnection

2012 ◽  
Vol 117 (A7) ◽  
pp. n/a-n/a ◽  
Author(s):  
Rongsheng Wang ◽  
Rumi Nakamura ◽  
Quanming Lu ◽  
Aimin Du ◽  
Tielong Zhang ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Magnetic Flux Ropes ◽  
Guide Field ◽  
Flux Ropes

scholarly journals Non-Gaussianity and cross-scale coupling in interplanetary magnetic field turbulence during a rope–rope magnetic reconnection event

2018 ◽  
Vol 36 (2) ◽  
pp. 497-507 ◽  
Author(s):  
Rodrigo A. Miranda ◽  
Adriane B. Schelin ◽  
Abraham C.-L. Chian ◽  
José L. Ferreira
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Coherent Structures ◽  
Flux Rope ◽  
Inertial Subrange ◽  
Order Moment ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Non Gaussian

Abstract. In a recent paper (Chian et al., 2016) it was shown that magnetic reconnection at the interface region between two magnetic flux ropes is responsible for the genesis of interplanetary intermittent turbulence. The normalized third-order moment (skewness) and the normalized fourth-order moment (kurtosis) display a quadratic relation with a parabolic shape that is commonly observed in observational data from turbulence in fluids and plasmas, and is linked to non-Gaussian fluctuations due to coherent structures. In this paper we perform a detailed study of the relation between the skewness and the kurtosis of the modulus of the magnetic field |B| during a triple interplanetary magnetic flux rope event. In addition, we investigate the skewness–kurtosis relation of two-point differences of |B| for the same event. The parabolic relation displays scale dependence and is found to be enhanced during magnetic reconnection, rendering support for the generation of non-Gaussian coherent structures via rope–rope magnetic reconnection. Our results also indicate that a direct coupling between the scales of magnetic flux ropes and the scales within the inertial subrange occurs in the solar wind. Keywords. Space plasma physics (turbulence)

Study of flux-rope characteristics at sub-astronomical-unit distances using the Helios 1 and 2 spacecraft

2020 ◽  
Vol 495 (2) ◽  
pp. 1566-1576
Author(s):  
Anil Raghav ◽  
Sandesh Gaikwad ◽  
Yuming Wang ◽  
Zubair I Shaikh ◽  
Wageesh Mishra ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Magnetic Energy ◽  
Ambient Medium ◽  
Flux Rope ◽  
Magnetic Clouds ◽  
Astronomical Unit ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
External Conditions ◽  
Internal Properties

ABSTRACT Magnetic flux ropes observed as magnetic clouds near 1 au have been extensively studied in the literature and their distinct features are derived using numerous models. These studies summarize the general characteristics of flux ropes at 1 au without providing an understanding of the continuous evolution of the flux ropes from near the Sun to 1 au. In the present study, we investigate 26 flux ropes observed by the Helios 1 and 2 spacecraft (from 0.3 to 1 au) using the velocity-modified Gold–Hoyle model. The correlation and regression analyses suggest that the expansion speed, poloidal speed, total magnetic helicity and twist per au of the flux rope are independent of heliospheric distance. The study implies that the aforementioned features are more strongly influenced by their internal properties compared with external conditions in the ambient medium. Moreover, the poloidal magnetic flux and magnetic energy of the studied flux ropes exhibit power-law dependence on heliospheric distance. A better understanding of the underlying physics and corroboration of these results is expected from the Parker Solar Probe measurements in the near future.

scholarly journals Confined and Eruptive Catastrophes of Solar Magnetic Flux Ropes Caused by Mass Loading and Unloading

2021 ◽  
Vol 921 (2) ◽  
pp. 172
Author(s):  
Quanhao Zhang ◽  
Rui Liu ◽  
Yuming Wang ◽  
Xiaolei Li ◽  
Shaoyu Lyu
Keyword(s):  
Magnetic Flux ◽  
Total Mass ◽  
Large Scale ◽  
Magnetic Energy ◽  
Flux Rope ◽  
Mass Loading ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Loading And Unloading ◽  
Rope System

Abstract It is widely accepted that coronal magnetic flux ropes are the core structures of large-scale solar eruptive activities, which have a dramatic impact on the solar-terrestrial system. Previous studies have demonstrated that varying magnetic properties of a coronal flux rope system could result in a catastrophe of the rope, which may trigger solar eruptive activities. Since the total mass of a flux rope also plays an important role in stabilizing the rope, we use 2.5 dimensional magnetohydrodynamic numerical simulations in this article to investigate how a flux rope evolves as its total mass varies. It is found that an unloading process that decreases the total mass of the rope could result in an upward (eruptive) catastrophe in the flux rope system, during which the rope jumps upward and the magnetic energy is released. This indicates that mass unloading processes could initiate the eruption of the flux rope. Moreover, when the system is not too diffusive, there is also a downward (confined) catastrophe that could be caused by mass loading processes via which the total mass accumulates. The magnetic energy, however, is increased during the downward catastrophe, indicating that mass loading processes could cause confined activities that may contribute to the storage of energy before the onset of coronal eruptions.

Interaction of Magnetic Flux Ropes Via Magnetic Reconnection Observed at the Magnetopause

2017 ◽  
Vol 122 (10) ◽  
pp. 10,436-10,447 ◽  
Author(s):  
Rongsheng Wang ◽  
Quanming Lu ◽  
Rumi Nakamura ◽  
Wolfgang Baumjohann ◽  
C. T. Russell ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Magnetic Flux Ropes ◽  
Flux Ropes

scholarly journals Evolution of Plasma Composition in an Eruptive Flux Rope

2022 ◽  
Vol 924 (1) ◽  
pp. 17
Author(s):  
D. Baker ◽  
L. M. Green ◽  
D. H. Brooks ◽  
P. Démoulin ◽  
L. van Driel-Gesztelyi ◽  
...  
Keyword(s):  
Magnetic Energy ◽  
Flux Rope ◽  
Plasma Composition ◽  
Imaging Spectrometer ◽  
Polarity Inversion ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
Free Magnetic Energy ◽  
Polarity Inversion Line ◽  
Euv Imaging

Abstract Magnetic flux ropes are bundles of twisted magnetic field enveloping a central axis. They harbor free magnetic energy and can be progenitors of coronal mass ejections (CMEs). However, identifying flux ropes on the Sun can be challenging. One of the key coronal observables that has been shown to indicate the presence of a flux rope is a peculiar bright coronal structure called a sigmoid. In this work, we show Hinode EUV Imaging Spectrometer observations of sigmoidal active region (AR) 10977. We analyze the coronal plasma composition in the AR and its evolution as a sigmoid (flux rope) forms and erupts as a CME. Plasma with photospheric composition was observed in coronal loops close to the main polarity inversion line during episodes of significant flux cancellation, suggestive of the injection of photospheric plasma into these loops driven by photospheric flux cancellation. Concurrently, the increasingly sheared core field contained plasma with coronal composition. As flux cancellation decreased and a sigmoid/flux rope formed, the plasma evolved to an intermediate composition in between photospheric and typical AR coronal compositions. Finally, the flux rope contained predominantly photospheric plasma during and after a failed eruption preceding the CME. Hence, plasma composition observations of AR 10977 strongly support models of flux rope formation by photospheric flux cancellation forcing magnetic reconnection first at the photospheric level then at the coronal level.

scholarly journals A new trigger mechanism for coronal mass ejections

2020 ◽  
Vol 644 ◽  
pp. A137
Author(s):  
A. W. James ◽  
L. M. Green ◽  
L. van Driel-Gesztelyi ◽  
G. Valori
Keyword(s):  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Extreme Ultraviolet ◽  
Flux Rope ◽  
Active Regions ◽  
Magnetic Activity ◽  
Trigger Mechanism ◽  
Magnetic Flux Rope ◽  
Left Handed ◽  
Flux Ropes

Context. Many previous studies have shown that the magnetic precursor of a coronal mass ejection (CME) takes the form of a magnetic flux rope, and a subset of them have become known as “hot flux ropes” due to their emission signatures in ∼10 MK plasma. Aims. We seek to identify the processes by which these hot flux ropes form, with a view of developing our understanding of CMEs and thereby improving space weather forecasts. Methods. Extreme-ultraviolet observations were used to identify five pre-eruptive hot flux ropes in the solar corona and study how they evolved. Confined flares were observed in the hours and days before each flux rope erupted, and these were used as indicators of episodic bursts of magnetic reconnection by which each flux rope formed. The evolution of the photospheric magnetic field was observed during each formation period to identify the process(es) that enabled magnetic reconnection to occur in the β <  1 corona and form the flux ropes. Results. The confined flares were found to be homologous events and suggest flux rope formation times that range from 18 hours to 5 days. Throughout these periods, fragments of photospheric magnetic flux were observed to orbit around each other in sunspots where the flux ropes had a footpoint. Active regions with right-handed (left-handed) twisted magnetic flux exhibited clockwise (anticlockwise) orbiting motions, and right-handed (left-handed) flux ropes formed. Conclusions. We infer that the orbital motions of photospheric magnetic flux fragments about each other bring magnetic flux tubes together in the corona, enabling component reconnection that forms a magnetic flux rope above a flaring arcade. This represents a novel trigger mechanism for solar eruptions and should be considered when predicting solar magnetic activity.

The evolution of magnetic flux ropes in sheared plasma flows

2000 ◽  
Vol 64 (1) ◽  
pp. 41-55 ◽  
Author(s):  
J. M. SCHMIDT ◽  
P. J. CARGILL
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Shear Layer ◽  
Cross Section ◽  
Circular Cross Section ◽  
Flux Rope ◽  
Plasma Pressure ◽  
Magnetic Flux Ropes ◽  
Flux Ropes ◽  
The Magnetic Field

The evolution of magnetic flux ropes in a sheared plasma flow is investigated. When the magnetic field outside the flux rope lies parallel to the axis of the flux rope, a flux rope of circular cross-section, whose centre is located at the midpoint of the shear layer, has its shape distorted, but remains in the shear layer. Small displacements of the flux-rope centre above or below the midpoint of the shear layer lead to the flux-rope being expelled from the shear layer. This motion arises because small asymmetries in the plasma pressure around the flux-rope boundary leads to a force that forces the flux rope into a region of uniform flow. When the magnetic field outside the flux rope lies in a plane perpendicular to the flux-rope axis, the flux rope and external magnetic field reconnect with each other, leading to the destruction of the flux rope.

Magnetic Reconnection in the Corona as a Source of Switchbacks in the Solar Wind

2021 ◽  
Author(s):  
James Drake ◽  
Oleksiy Agapitov ◽  
Marc Swisdak ◽  
Sam Badman ◽  
Stuart Bale ◽  
...  
Keyword(s):  
Solar Wind ◽  
Magnetic Reconnection ◽  
Coronal Hole ◽  
Flux Rope ◽  
Magnetic Flux Ropes ◽  
Guide Field ◽  
Large Numbers ◽  
Flux Ropes ◽  
Environment Characteristic ◽  
Field Lines

&lt;p&gt;The observations from the Parker Solar Probe during the first&lt;br&gt;perihelion revealed large numbers of local reversals in the radial&lt;br&gt;component of the magnetic field with associated velocity spikes. Since&lt;br&gt;the spacecraft was magnetically connected to a coronal hole during the&lt;br&gt;closest approach to the sun, one possible source of these spikes is&lt;br&gt;magnetic reconnection between the open field lines in the coronal hole&lt;br&gt;and an adjacent region of closed flux. Reconnection in a low beta&lt;br&gt;environment characteristic of the corona is expected to be bursty&lt;br&gt;rather than steady and is therefore capable of producing large numbers&lt;br&gt;of magnetic flux ropes with local reversals of the radial magnetic&lt;br&gt;field that can propagate outward large radial distances from the&lt;br&gt;sun. Flux ropes with a strong guide field produce signatures&lt;br&gt;consistent with the PSP observations. We have carried out simulations&lt;br&gt;of &quot;interchange&quot; reconnection in the corona and have explored the&lt;br&gt;local structure of flux ropes embedded within the expanding solar&lt;br&gt;wind. We have first established that traditional interchange&lt;br&gt;reconnection cannot produce the switchbacks since bent field lines&lt;br&gt;generated in the corona quickly straighten. The simulations have been&lt;br&gt;extended to the regime dominated by the production of multiple flux&lt;br&gt;ropes and we have established that flux ropes are injected into the&lt;br&gt;local solar wind. Local simulations of reconnection are also being&lt;br&gt;carried out to explore the structure of flux ropes embedded in the&lt;br&gt;solar wind for comparison with observations. Evidence is presented&lt;br&gt;that flux rope merging may be ongoing and might lead to the high&lt;br&gt;aspect ratio of the switchback structures measured in the solar wind.&lt;/p&gt;

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