Magnetic flux array for spontaneous magnetic reconnection experiments

2008 ◽  
Vol 79 (6) ◽  
pp. 063505 ◽  
Author(s):  
A. Kesich ◽  
J. Bonde ◽  
J. Egedal ◽  
W. Fox ◽  
R. Goodwin ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Magnetic Reconnection

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 Turbulence and dynamo interlinks

2012 ◽  
Vol 8 (S294) ◽  
pp. 337-348
Author(s):  
E. M. de Gouveia Dal Pino ◽  
R. Santos-Lima ◽  
G. Kowal ◽  
D. Falceta-Gonçalves
Keyword(s):  
Magnetic Fields ◽  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Small Scale ◽  
Low Density ◽  
Mhd Turbulence ◽  
Turbulent Dynamo ◽  
Dynamo Process

AbstractThe role of turbulence in astrophysical environments and its interplay with magnetic fields is still highly debated. In this lecture, we will discuss this issue in the framework of dynamo processes. We will first present a very brief summary of turbulent dynamo theories, then will focus on small scale turbulent dynamos and their particular relevance on the origin and maintenance of magnetic fields in the intra-cluster media (ICM) of galaxies. In these environments, the very low density of the flow requires a collisionless-MHD treatment. We will show the implications of this approach in the turbulent amplification of the magnetic fields in these environments. To finalize, we will also briefly address the connection between MHD turbulence and fast magnetic reconnection and its possible implications in the diffusion of magnetic flux in the dynamo process.

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 Ellerman bombs and UV bursts: reconnection at different atmospheric layers

2020 ◽  
Vol 633 ◽  
pp. A58 ◽  
Author(s):  
Ada Ortiz ◽  
Viggo H. Hansteen ◽  
Daniel Nóbrega-Siverio ◽  
Luc Rouppe van der Voort
Keyword(s):  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Transition Region ◽  
Spatial Relationship ◽  
Spectral Lines ◽  
Near Ultraviolet ◽  
Temporal And Spatial ◽  
Imaging Spectrograph ◽  
High Cadence ◽  
Ellerman Bombs

The emergence of magnetic flux through the photosphere and into the outer solar atmosphere produces, amongst other dynamical phenomena, Ellerman bombs (EBs), which are observed in the wings of Hα and are due to magnetic reconnection in the photosphere below the chromospheric canopy. Signs of magnetic reconnection are also observed in other spectral lines, typical of the chromosphere or the transition region. An example are the ultraviolet (UV) bursts observed in the transition region lines of Si IV and the upper chromospheric lines of Mg II. In this work we analyze high-cadence, high-resolution coordinated observations between the Swedish 1m Solar Telescope (SST) and the Interface Region Imaging Spectrograph (IRIS) spacecraft. Hα images from the SST provide us with the positions, timings, and trajectories of EBs in an emerging flux region. Simultaneous, co-aligned IRIS slit-jaw images at 133 (C II, transition region), 140 (Si IV, transition region), and 279.6 (Mg II k, core, upper chromosphere) nm as well as spectroscopy in the far- and near-ultraviolet from the fast spectrograph raster allow us to study the possible chromospheric and transition region counterparts of those EBs. Our main goal is to study the possible temporal and spatial relationship between several reconnection events at different layers in the atmosphere (namely EBs and UV bursts), the timing history between them, and the connection of these dynamical phenomena to the ejection of surges in the chromosphere. We also investigate the properties of an extended UV burst and their variations across the burst domain. Our results suggest a scenario where simultaneous and co-spatial EBs and UV bursts are part of the same reconnection system occurring sequentially along a vertical or nearly vertical current sheet. Heating and bidirectional jets trace the location where reconnection takes place. These results support and expand those obtained from recent numerical simulations of magnetic flux emergence.

scholarly journals Numerical Simulation of the Explosive Events in the Solar Atmosphere

1993 ◽  
Vol 141 ◽  
pp. 134-137
Author(s):  
Shu-Ping Jiu
Keyword(s):  
Numerical Simulation ◽  
Magnetic Flux ◽  
Magnetic Reconnection ◽  
Solar Atmosphere ◽  
Plasma Flow ◽  
Small Scale ◽  
Flare Activity ◽  
Specific Location ◽  
Mhd Simulations ◽  
Explosive Events

AbstractExplosive events are the earliest indicators of flare activity and potentially predict the imminent occurrence of a flare at a specific location. They are highly energetic small-scale phenomena which are frequently detected throughout the quiet and active sun. The observations show that explosive events are related to emerging magnetic flux and tend to occur on the edges of high photospheric magnentic field regions. The cancellation of photospheric magnetic flux are the manifestation of explosive events, so that they are identified as the magnetic reconnection of flux elements. We assume that emerging flux are convected to the network boundaries with the typical velocity of intranetwork elements. Two-dimension (2D) compressible MHD simulations are performed to explore the reconnection process between emerging intranework flux and network field. The numerical results clearly show the cancellation of magnetic flux and the acceleration of the plasma flow.

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 MHD turbulence-Star Formation Connection: from pc to kpc scales

2010 ◽  
Vol 6 (S274) ◽  
pp. 333-339 ◽  
Author(s):  
E. M. de Gouveia Dal Pino ◽  
R. Santos-Lima ◽  
A. Lazarian ◽  
M. R. M. Leão ◽  
D. Falceta-Gonçalves ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Magnetic Flux ◽  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Turbulent Flows ◽  
Molecular Clouds ◽  
Three Dimensional ◽  
Mhd Turbulence ◽  
Star Forming

AbstractThe transport of magnetic flux to outside of collapsing molecular clouds is a required step to allow the formation of stars. Although ambipolar diffusion is often regarded as a key mechanism for that, it has been recently argued that it may not be efficient enough. In this review, we discuss the role that MHD turbulence plays in the transport of magnetic flux in star forming flows. In particular, based on recent advances in the theory of fast magnetic reconnection in turbulent flows, we will show results of three-dimensional numerical simulations that indicate that the diffusion of magnetic field induced by turbulent reconnection can be a very efficient mechanism, especially in the early stages of cloud collapse and star formation. To conclude, we will also briefly discuss the turbulence-star formation connection and feedback in different astrophysical environments: from galactic to cluster of galaxy scales.

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)

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