Double‐peaked core field of flux ropes during magnetic reconnection

2017 ◽  
Vol 122 (6) ◽  
pp. 6374-6384 ◽  
Author(s):  
Chaoxu Liu ◽  
Xueshang Feng ◽  
Rumi Nakamura ◽  
Jianpeng Guo ◽  
Rongsheng Wang
Keyword(s):  
Magnetic Reconnection ◽  
Core Field ◽  
Flux Ropes

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 Transient and localized processes in the magnetotail: a review

2008 ◽  
Vol 26 (4) ◽  
pp. 955-1006 ◽  
Author(s):  
A. S. Sharma ◽  
R. Nakamura ◽  
A. Runov ◽  
E. E. Grigorenko ◽  
H. Hasegawa ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Current Sheet ◽  
Spatial Scales ◽  
Theoretical Models ◽  
Particle Interactions ◽  
Transient Field ◽  
Theoretical Frameworks ◽  
Flux Ropes ◽  
Night Side ◽  
Bursty Bulk Flows

Abstract. Many phenomena in the Earth's magnetotail have characteristic temporal scales of several minutes and spatial scales of a few Earth radii (RE). Examples of such transient and localized mesoscale phenomena are bursty bulk flows, beamlets, energy dispersed ion beams, flux ropes, traveling compression regions, night-side flux transfer events, and rapid flappings of the current sheet. Although most of these observations are linked to specific interpretations or theoretical models they are inter-related and can be the different aspects of a physical process or origin. Recognizing the inter-connected nature of the different transient and localized phenomena in the magnetotail, this paper reviews their observations by highlighting their important characteristics, with emphasis on the new results from Cluster multipoint observations. The multi-point Cluster measurements have provided, for the first time, the ability to distinguish between temporal and spatial variations, and to resolve spatial structures. Some examples of the new results are: flux ropes with widths of 0.3 RE, transient field aligned currents associated with bursty bulk flows and connected to the Hall current at the magnetic reconnection, flappings of the magnetotail current sheet with time scales of 100 s–10 min and thickness of few thousand km, and particle energization including velocity and time dispersed ion structures with the latter having durations of 1–3 min. The current theories of these transient and localized processes are based largely on magnetic reconnection, although the important role of the interchange and other plasma modes are now well recognized. On the kinetic scale, the energization of particles takes place near the magnetic X-point by non-adiabatic processes and wave-particle interactions. The theory, modeling and simulations of the plasma and field signatures are reviewed and the links among the different observational concepts and the theoretical frameworks are discussed. The mesoscale processes in the magnetotail and the strong coupling among them are crucial in developing a comprehensive understanding of the multiscale phenomena of the magnetosphere.

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.

scholarly journals Cluster observations of flux rope structures in the near-tail

2006 ◽  
Vol 24 (2) ◽  
pp. 651-666 ◽  
Author(s):  
P. D. Henderson ◽  
C. J. Owen ◽  
I. V. Alexeev ◽  
J. Slavin ◽  
A. N. Fazakerley ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Sheet ◽  
Lower Estimate ◽  
Flux Rope ◽  
Plasma Pressure ◽  
Magnetic Pressure ◽  
Total Force ◽  
Core Field ◽  
Flux Ropes ◽  
The Magnetic Field

Abstract. An investigation of the 2003 Cluster tail season has revealed small flux ropes in the near-tail plasma sheet of Earth. These flux ropes manifest themselves as a bipolar magnetic field signature (usually predominantly in the Z-component) associated with a strong transient peak in one or more of the other components (usually the Y-component). These signatures are interpreted as the passage of a cylindrical magnetic structure with a strong axial magnetic field over the spacecraft position. On the 2 October 2003 all four Cluster spacecraft observed a flux rope in the plasma sheet at X (GSM) ~-17 RE. The flux rope was travelling Earthward and duskward at ~160 kms-1, as determined from multi-spacecraft timing. This is consistent with the observed south-then-north bipolar BZ signature and corresponds to a size of ~0.3 RE (a lower estimate, measuring between the inflection points of the bipolar signature). The axis direction, determined from multi-spacecraft timing and the direction of the strong core field, was close to the intermediate variance direction of the magnetic field. The current inside the flux rope, determined from the curlometer technique, was predominantly parallel to the magnetic field. However, throughout the flux rope, but more significant in the outer sections, a non-zero component of current perpendicular to the magnetic field existed. This shows that the flux rope was not in a "constant α" force-free configuration, i.e. the magnetic force, J×B was also non-zero. In the variance frame of the magnetic field, the components of J×B suggest that the magnetic pressure force was acting to expand the flux rope, i.e. directed away from the centre of the flux rope, whereas the smaller magnetic tension force was acting to compress the flux rope. The plasma pressure is reduced inside the flux rope. A simple estimate of the total force acting on the flux rope from the magnetic forces and surrounding plasma suggests that the flux rope was experiencing an expansive total force. On 13 August 2003 all four Cluster spacecraft observed a flux rope at X (GSM) ~-18 RE. This flux rope was travelling tailward at 200 kms-1, consistent with the observed north-then-south bipolar BZ signature. The bipolar signature corresponds to a size of ~0.3 RE (lower estimate). In this case, the axis, determined from multi-spacecraft timing and the direction of the strong core field, was directed close to the maximum variance direction of the magnetic field. The current had components both parallel and perpendicular to the magnetic field, and J×B was again larger in the outer sections of the flux rope than in the centre. This flux rope was also under expansive magnetic pressure forces from J×B, i.e. directed away from the centre of the flux rope, and had a reduced plasma pressure inside the flux rope. A simple total force calculation suggests that this flux rope was experiencing a large expansive total force. The observations of a larger J×B signature in the outer sections of the flux ropes when compared to the centre may be explained if the flux ropes are observed at an intermediate stage of their evolution after creation by reconnection at multiple X lines near the Cluster apogee. It is suggested that these flux ropes are in the process of relaxing towards the force-free like configuration often observed further down the tail. The centre of the flux ropes may contain older reconnected flux at a later evolutionary stage and may therefore be more force-free.

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.

MMS observations of explosive filamentary current within two adjacent ion scale flux ropes

2021 ◽  
Author(s):  
Yuchen Xiao ◽  
Shutao Yao ◽  
Ruilong Guo ◽  
Quanqi Shi ◽  
Anmin Tian ◽  
...  
Keyword(s):  
Particle Acceleration ◽  
Energy Dissipation ◽  
Magnetic Reconnection ◽  
Temporal Resolution ◽  
Pitch Angle ◽  
Angle Distribution ◽  
Pitch Angle Distribution ◽  
The Past ◽  
Flux Ropes ◽  
Spatio Temporal

&lt;p&gt;Flux ropes have attracted extensive attention due to their importance in studying instantaneous magnetic reconnection&amp;#160;over the past years. Recently, with the improvement of high spatio-temporal resolution measurements, kinetic-scale flux ropes have been detected. However, their generation&amp;#160;and energy energization are still unclear. In this study, electron-scale filamentary&amp;#160;currents&amp;#160;within&amp;#160;two adjacent ion scale flux ropes&amp;#160;are observed&amp;#160;using MMS data. We find that:&lt;/p&gt;&lt;p&gt;1. Intense and explosive filamentary currents in parallel and perpendicular directions are found inside the flux ropes.&lt;/p&gt;&lt;p&gt;2. The electron pitch angle distribution appears &quot;X&quot; like shape, and could be caused by the electron acceleration.&lt;/p&gt;&lt;p&gt;3. The filamentary current appears in the center of the &quot;X&quot; distribution.&lt;/p&gt;&lt;p&gt;The filamentary currents are important and are considered to be the evidence of secondary reconnection&amp;#160;[Wang et al.,&amp;#160;2020]. The&amp;#160;observations in our study are&amp;#160;important&amp;#160;to reveal the particle acceleration&amp;#160;and energy dissipation in&amp;#160;magnetic reconnection.&lt;/p&gt;

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)

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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