scholarly journals Evidence of transient reconnection in the outflow jet of primary reconnection site

2014 ◽  
Vol 32 (3) ◽  
pp. 239-248 ◽  
Author(s):  
R. Wang ◽  
R. Nakamura ◽  
T. Zhang ◽  
A. Du ◽  
W. Baumjohann ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Observational Evidence ◽  
Generation Mechanism ◽  
Magnetic Islands ◽  
Magnetic Island ◽  
Subsequent Evolution ◽  
Reconnection Site

Abstract. The precise mechanism for the formation of magnetic islands in the magnetotail and the subsequent evolution are still controversial. New investigations have provided the first observational evidence of secondary reconnection in the earthward outflow jet of primary reconnection in the magnetotail. The secondary reconnection takes place 38 c/ωpi earthward from the primary reconnection site and results in the birth of a magnetic island observed. This generation mechanism is different from the widely used model of multiple reconnection X-lines. The duration of the secondary reconnection was approximate one ion gyration period (5 s). The observations resemble recent numerical simulations where magnetic reconnection could spontaneously and transiently happen in the outflow jet, called secondary reconnection, which was used to explain the formation of the dipolarization fronts. Coincidentally, another magnetic island moving earthward passed through three satellites successively. By this chance we find the magnetic island was accelerated towards Earth with an acceleration of about 9 km s−2 at −19 RE in the magnetotail.

scholarly journals Effects of plasma turbulence on the nonlinear evolution of magnetic island in tokamak

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Minjun J. Choi ◽  
Lāszlo Bardōczi ◽  
Jae-Min Kwon ◽  
T. S. Hahm ◽  
Hyeon K. Park ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Nonlinear Evolution ◽  
Plasma Turbulence ◽  
Magnetized Plasmas ◽  
Tokamak Plasmas ◽  
Magnetic Islands ◽  
Magnetic Island ◽  
Reconnection Site ◽  
Ambient Turbulence

AbstractMagnetic islands (MIs), resulting from a magnetic field reconnection, are ubiquitous structures in magnetized plasmas. In tokamak plasmas, recent researches suggested that the interaction between an MI and ambient turbulence can be important for the nonlinear MI evolution, but a lack of detailed experimental observations and analyses has prevented further understanding. Here, we provide comprehensive observations such as turbulence spreading into an MI and turbulence enhancement at the reconnection site, elucidating intricate effects of plasma turbulence on the nonlinear MI evolution.

scholarly journals MHD Numerical Simulations of Magnetic Reconnection Associated with Emerging Flux

1993 ◽  
Vol 141 ◽  
pp. 500-503
Author(s):  
K. Shibata ◽  
S. Nozawa ◽  
R. Matsumoto
Keyword(s):  
Magnetic Field ◽  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Coronal Magnetic Field ◽  
Two Dimensional ◽  
Magnetic Islands ◽  
X Ray ◽  
Hot Plasma ◽  
Mass Ejection ◽  
Coronal Field

AbstractTwo-dimensional (2D) magnetohydrodynamic (MHD) numerical simulations have been performed to study magnetic reconnection between emerging flux and the overlying coronal magnetic field, taking into account of gravity. It is found that (1) reconnection starts when most of chromospheric mass in the current sheet between the emerging flux and the coronal field has drained down along the loop because of gravity, (2) multiple magnetic islands, which confine cool, dense chromospheric plasma, are created in the sheet; the islands coalesce dynamically and are ejected along the sheet, together with the ambient hot plasma, at Alfven speed. The coexistence of hot and cool plasmas in the mass ejection (jet) associated with the reconnection seems to explain those X-ray jets observed by Yohkoh, which are identified with Hα surges.

scholarly journals The Location of Magnetic Reconnection at Earth’s Magnetopause

2021 ◽  
Vol 217 (3) ◽  
Author(s):  
K. J. Trattner ◽  
S. M. Petrinec ◽  
S. A. Fuselier
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Ion Beams ◽  
Review Article ◽  
Observational Evidence ◽  
Magnetic Shear ◽  
General Direction ◽  
Shear Model ◽  
Wide Range

AbstractOne of the major questions about magnetic reconnection is how specific solar wind and interplanetary magnetic field conditions influence where reconnection occurs at the Earth’s magnetopause. There are two reconnection scenarios discussed in the literature: a) anti-parallel reconnection and b) component reconnection. Early spacecraft observations were limited to the detection of accelerated ion beams in the magnetopause boundary layer to determine the general direction of the reconnection X-line location with respect to the spacecraft. An improved view of the reconnection location at the magnetopause evolved from ionospheric emissions observed by polar-orbiting imagers. These observations and the observations of accelerated ion beams revealed that both scenarios occur at the magnetopause. Improved methodology using the time-of-flight effect of precipitating ions in the cusp regions and the cutoff velocity of the precipitating and mirroring ion populations was used to pinpoint magnetopause reconnection locations for a wide range of solar wind conditions. The results from these methodologies have been used to construct an empirical reconnection X-line model known as the Maximum Magnetic Shear model. Since this model’s inception, several tests have confirmed its validity and have resulted in modifications to the model for certain solar wind conditions. This review article summarizes the observational evidence for the location of magnetic reconnection at the Earth’s magnetopause, emphasizing the properties and efficacy of the Maximum Magnetic Shear Model.

scholarly journals Modeling of magnetic island formation in magnetic reconnection experiment

1999 ◽  
Vol 6 (4) ◽  
pp. 1253-1257 ◽  
Author(s):  
T.-H. Watanabe ◽  
T. Hayashi ◽  
T. Sato ◽  
M. Yamada ◽  
H. Ji
Keyword(s):  
Magnetic Reconnection ◽  
Magnetic Island ◽  
Island Formation

scholarly journals Collinder 135 and UBC 7: A physical pair of open clusters

2020 ◽  
Vol 642 ◽  
pp. L4
Author(s):  
Dana A. Kovaleva ◽  
Marina Ishchenko ◽  
Ekaterina Postnikova ◽  
Peter Berczik ◽  
Anatoly E. Piskunov ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Observational Evidence ◽  
Open Clusters ◽  
Line Of Sight ◽  
Kinematic Parameters ◽  
Current Line ◽  
Chance Coincidence ◽  
The Past ◽  
Link Type ◽  
Spatial Coordinates

Context. Given the closeness of the two open clusters Collinder 135 and UBC 7 on the sky, we investigate the possibility that the two clusters are physically related. Aims. We aim to recover the present-day stellar membership in the open clusters Cr 135 and UBC 7 (300 pc from the Sun) in order to constrain their kinematic parameters, ages, and masses and to restore their primordial phase space configuration. Methods. The most reliable cluster members are selected with our traditional method modified for the use of Gaia DR2 data. Numerical simulations use the integration of cluster trajectories backwards in time with our original high-order Hermite4 code φ−GRAPE. Results. We constrain the age, spatial coordinates, velocities, radii, and masses of the clusters. We estimate the actual separation of the cluster centres equal to 24 pc. The orbital integration shows that the clusters were much closer in the past if their current line-of-sight velocities are very similar and the total mass is more than seven times larger than the mass of the most reliable members. Conclusions. We conclude that the two clusters Cr 135 and UBC 7 might very well have formed a physical pair based on the observational evidence as well as numerical simulations. The probability of a chance coincidence is only about 2%.

scholarly journals Corotating Magnetic Reconnection Site in Saturn’s Magnetosphere

2017 ◽  
Vol 846 (2) ◽  
pp. L25 ◽  
Author(s):  
Z. H. Yao ◽  
A. J. Coates ◽  
L. C. Ray ◽  
I. J. Rae ◽  
D. Grodent ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Reconnection Site

Magnetic island suppression by electron cyclotron current drive as converse of a forced reconnection problem

2018 ◽  
Vol 84 (3) ◽  
Author(s):  
D. Grasso ◽  
D. Borgogno ◽  
L. Comisso ◽  
E. Lazzaro
Keyword(s):  
Robust Control ◽  
Control Strategy ◽  
Electron Cyclotron ◽  
Current Drive ◽  
Magnetic Islands ◽  
Tearing Mode ◽  
Magnetic Island ◽  
Technical Approach ◽  
Physical Conditions ◽  
Secondary Instabilities

This paper addresses one aspect of the problem of the suppression of tearing mode magnetic islands by electron cyclotron current drive (ECCD) injection, formulating the problem as the converse of a forced reconnection problem. New physical conditions are discussed which should be considered in the technical approach towards a robust control strategy. Limits on the ECCD deposition are determined to avoid driving the system into regimes where secondary instabilities develop. Numerical simulations confirming the theory are also presented.

scholarly journals Quasi-separatrix Layers Induced by Ballooning Instability in Near-Earth Magnetotail

2019 ◽  
Author(s):  
Ping Zhu ◽  
Zechen Wang ◽  
Jun Chen ◽  
Xingting Yan ◽  
Rui Liu
Keyword(s):  
Numerical Simulations ◽  
Magnetic Reconnection ◽  
Solar Physics ◽  
Close Correlation ◽  
Satellite Observations ◽  
Two Dimensional ◽  
3 Dimensional ◽  
Ballooning Instability ◽  
3D Geometry ◽  
Alternative Means

Abstract. Magnetic reconnection processes in the near-Earth magnetotail can be highly 3-dimensional (3D) in geometry and dynamics, even though the magnetotail configuration itself is nearly two dimensional due to the symmetry in the dusk-dawn direction. Such reconnection processes can be induced by the 3D dynamics of nonlinear ballooning instability. In this work, we explore the global 3D geometry of the reconnection process induced by ballooning instability in the near-Earth magnetotail by examining the distribution of quasi-separatrix layers associated with plasmoid formation in the entire 3D domain of magnetotail configuration, using an algorithm previously developed in context of solar physics. The 3D distribution of quasi-separatrix layers (QSLs) as well as their evolution directly follows the plasmoid formation during the nonlinear development of ballooning instability in both time and space. Such a close correlation demonstrates a strong coupling between the ballooning and the corresponding reconnection processes. It further confirms the intrinsic 3D nature of the ballooning-induced plasmoid formation and reconnection processes, in both geometry and dynamics. In addition, the reconstruction of the 3D QSL geometry may provide an alternative means for identifying the location and timing of 3D reconnection sites in magnetotail from both numerical simulations and satellite observations.

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