scholarly journals Electron flat-top distributions around the magnetic reconnection region

2008 ◽  
Vol 113 (A1) ◽  
pp. n/a-n/a ◽  
Author(s):  
Y. Asano ◽  
R. Nakamura ◽  
I. Shinohara ◽  
M. Fujimoto ◽  
T. Takada ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Reconnection Region

scholarly journals Heavy ion escape from Martian wake enhanced by magnetic reconnection

2021 ◽  
Author(s):  
Lei Wang ◽  
Can Huang ◽  
Yasong Ge ◽  
A. M. Du ◽  
Rongsheng Wang ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Flux Rope ◽  
Heavy Ion ◽  
Escape Rate ◽  
Wake Region ◽  
Atmospheric Evolution ◽  
Oxygen Ions ◽  
Plasma Environment ◽  
Ion Escape ◽  
Reconnection Region

Abstract How ion escape from the near-Mars space is one of the biggest puzzles for understanding the atmospheric evolution of Mars. Ions in the plasma wake region continuously escape from the unmagnetized planet. Although the average ion escape rate in the wake region is relatively low, observations also have revealed the presence of events that contribute bursty and enhanced ion escape fluxes. Boundary instabilities and magnetic reconnection are suggested to be the candidate mechanisms. However, there is a lack of evaluation of ion escape caused by reconnection and comparison of the two mechanisms under a similar plasma environment. Here, we show an exciting reconnection event in the Martian wake. Two types of flux ropes are observed during the event. One was generated by reconnection, while others were produced by dayside boundary instability and convected to tail. The escape rate of oxygen ions in the reconnection region was estimated to be about 53–72% of the total tailward escape. Furthermore, the escape flux in the flux rope produced by reconnection was over twice that caused by dayside instabilities.

scholarly journals Scaling of magnetic reconnection with a limited x-line extent

2021 ◽  
Author(s):  
Kai Huang ◽  
Yi-Hsin Liu ◽  
Quanming Lu ◽  
Michael Hesse
Keyword(s):  
Magnetic Reconnection ◽  
Magnetic Energy ◽  
Well Being ◽  
Reconnection Rate ◽  
Flux Transport ◽  
Speed Reduction ◽  
Reconnection Region ◽  
Line Asymmetry ◽  
Fundamental Physical ◽  
Suppression Region

<p>Magnetic reconnection is a fundamental physical process that is responsible for releasing the magnetic energy during substorms of planetary magnetotails. Previous studies of magnetic reconnection usually take the two-dimensional (2D) approach, which assumes that reconnection is uniform in the 3rd direction out of the 2D reconnection plane. However, observations suggest that reconnection can be limited in the 3rd direction, such as reconnection at Mercury's magnetotail. It turns out that reconnection can be suppressed when reconnection region is very limited in the 3rd direction. An internal x-line asymmetry along the current direction develops because of the transport of reconnected magnetic flux by electrons beneath the ion kinetic scale, resulting in a suppression region identified in Liu et al., 2019. Under the guidance of a series of 3D kinetic simulations, in this work, we incorporate the length-scale of this suppression region ~10d<sub>i</sub> to quantitatively model the reduction of the reconnection rate and the maximum outflow speed observed in the short x-line limit. The average reconnection rate drops because of the limited active region (where the current sheet thins down to the electron inertial scale) within an x-line. The outflow speed reduction correlates with the decrease of the <strong>J</strong>×<strong>B</strong> force, that can be modeled by the phase shift between the <strong>J</strong> and <strong>B</strong> profiles, also as a consequence of the flux transport. Notably, these two quantities are most essential in defining the well-being of magnetic reconnection, which can tell us when reconnection shall be suppressed.</p>

scholarly journals Proton Acceleration near an X‐Type Magnetic Reconnection Region

1998 ◽  
Vol 494 (1) ◽  
pp. 430-437 ◽  
Author(s):  
Ken‐ichi Mori ◽  
Jun‐ichi Sakai ◽  
Jie Zhao
Keyword(s):  
Magnetic Reconnection ◽  
Proton Acceleration ◽  
Reconnection Region

scholarly journals Magnetic reconnection driven by filament eruption in the 7 June 2011 event

2013 ◽  
Vol 8 (S300) ◽  
pp. 502-503
Author(s):  
L. van Driel-Gesztelyi ◽  
D. Baker ◽  
T. Török ◽  
E. Pariat ◽  
L. M. Green ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Filament Eruption ◽  
Mhd Simulations ◽  
Reconnection Region ◽  
Solar Eruptions ◽  
Magnetic Modelling ◽  
First Time

AbstractDuring an unusually massive filament eruption on 7 June 2011, SDO/AIA imaged for the first time significant EUV emission around a magnetic reconnection region in the solar corona. The reconnection occurred between magnetic fields of the laterally expanding CME and a neighbouring active region. A pre-existing quasi-separatrix layer was activated in the process. This scenario is supported by data-constrained numerical simulations of the eruption. Observations show that dense cool filament plasma was re-directed and heated in situ, producing coronal-temperature emission around the reconnection region. These results provide the first direct observational evidence, supported by MHD simulations and magnetic modelling, that a large-scale re-configuration of the coronal magnetic field takes place during solar eruptions via the process of magnetic reconnection.

scholarly journals A solar filament disconnected by magnetic reconnection

2020 ◽  
Vol 633 ◽  
pp. A121
Author(s):  
Zhike Xue ◽  
Xiaoli Yan ◽  
Liheng Yang ◽  
Jincheng Wang ◽  
Qiaoling Li ◽  
...  
Keyword(s):  
Active Region ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Lower Atmosphere ◽  
Mean Velocity ◽  
Reconnection Region ◽  
Resolution Observation ◽  
Solar Filament ◽  
Reconnection Site ◽  
The Right

Aims. We aim to study a high-resolution observation of an asymmetric inflow magnetic reconnection between a filament and its surrounding magnetic loops in active region NOAA 12436 on 2015 October 23. Methods. We analyzed the multiband observations of the magnetic reconnection obtained by the New Vacuum Solar Telescope (NVST) and the Solar Dynamic Observatory. We calculated the NVST Hα Dopplergrams to determine the Doppler properties of the magnetic reconnection region and the rotation of a jet. Results. The filament firstly becomes active and then approaches its southwestern surrounding magnetic loops (L1) with a velocity of 9.0 km s−1. During this period, the threads of the filament become loose in the reconnection region and then reconnect with L1 in turn. L1 is pressed backward by the filament with a velocity of 5.5 km s−1, and then the magnetic reconnection occurs between them. A set of newly formed loops are separated from the reconnection site with a mean velocity of 127.3 km s−1. In the middle stage, some threads of the filament return back first with a velocity of 20.1 km s−1, and others return with a velocity of 4.1 km s−1 after about 07:46 UT. Then, L1 also begins to return with a velocity of 3.5 km s−1 at about 07:47 UT. At the same time, magnetic reconnection continues to occur between them until 07:51 UT. During the reconnection, a linear typical current sheet forms with a length of 5.5 Mm and a width of 1.0 Mm, and a lot of hot plasma blobs are observed propagating from the typical current sheet. During the reconnection, the plasma in the reconnection region and the typical current sheet always shows redshifted feature. Furthermore, the material and twist of the filament are injected into the newly longer-formed magnetic loops by the magnetic reconnection, which leads to the formation of a jet, and its rotation. Conclusions. The observational evidence for the asymmetric inflow magnetic reconnection is investigated. We conclude that the magnetic reconnection does occur in this event and results in the disconnection of the filament. The looseness of the filament may be due to the pressure imbalance between the inside and outside of the filament. The redshifted feature in the reconnection site can be explained by the expansion of the right flank of the filament to the lower atmosphere because of the complex magnetic configuration in this active region.

scholarly journals On the longitudinal extent of magnetopause reconnection pulses

1996 ◽  
Vol 14 (9) ◽  
pp. 865-878 ◽  
Author(s):  
M. Lockwood ◽  
C. J. Davis
Keyword(s):  
Magnetic Reconnection ◽  
Local Time ◽  
Magnetic Local Time ◽  
Dispersion Characteristics ◽  
Low Latitude ◽  
Ion Injection ◽  
Reconnection Region ◽  
Transient Events ◽  
Magnetopause Reconnection

Abstract. The open magnetosphere model of cusp ion injection, acceleration and precipitation is used to predict the dispersion characteristics for fully pulsed magnetic reconnection at a low-latitude magnetopause X-line. The resulting steps, as would be seen by a satellite moving meridionally and normal to the ionospheric projection of the X-line, are compared with those seen by satellites moving longitudinally, along the open/closed boundary. It is shown that two observed cases can be explained by similar magnetosheath and reconnection characteristics, and that the major differences between them are well explained by the different satellite paths through the events. Both cases were observed in association with poleward-moving transient events seen by ground-based radar, as also predicted by the theory. The results show that the reconnection is pulsed but strongly imply it cannot also be spatially patchy, in the sense of isolated X-lines which independently are intermittently active. Furthermore they show that the reconnection pulses responsible for the poleward-moving events and the cusp ion steps, must cover at least 3 h of magnetic local time, although propagation of the active reconnection region may mean that it does not extend this far at any one instant of time.

scholarly journals A magnetic reconnection model for hot explosions in the cool atmosphere of the Sun

2021 ◽  
Author(s):  
Lei Ni
Keyword(s):  
Magnetic Reconnection ◽  
Current Sheet ◽  
Large Temperature ◽  
Formation Mechanisms ◽  
Line Profiles ◽  
Turbulent Structures ◽  
Plasma Parameters ◽  
Magnetic Diffusivity ◽  
Reconnection Region ◽  
Initial Plasma

<p>UV bursts and Ellerman bombs are transient brightenings observed in the low solar atmospheres of emerging flux regions. Observations have discovered the cospatial and cotemporal EBs and UV bursts, and their formation mechanisms are still not clear. The multi-thermal components with a large temperature span in these events challenge our understanding of magnetic reconnection and heating mechanisms in the low solar atmosphere. We have studied magnetic reconnection between the emerging and background magnetic fields. The initial plasma parameters are based on the C7 atmosphere model. After the current sheet with dense photosphere plasma is emerged to <span tabindex="0" role="presentation" data-mathml='<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>0.5</mn></math>'><span><span><span>0.5</span></span></span></span> Mm above the solar surface, plasmoid instability appears. The plasmoids collide and coalesce with each other, which makes the plasmas with different densities and temperatures mixed up in the turbulent reconnection region. Therefore, the hot plasmas corresponding to the UV emissions and colder plasmas corresponding to the emissions from other wavelenghts can move together and occur at about the same height. In the meantime, the hot turbulent structures basically concentrate above <span tabindex="0" role="presentation" data-mathml='<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>0.4</mn></math>'><span><span><span>0.4</span></span></span></span> Mm, whereas the cool plasmas extend to much lower heights to the bottom of the current sheet. These phenomena are consistent with the observations of Chen et al. 2019, ApJL. The synthesized Si IV line profiles are similar to the observed one in UV bursts, the enhanced wing of the line profiles can extend to about <span tabindex="0" role="presentation" data-mathml='<math xmlns="http://www.w3.org/1998/Math/MathML"><mn>100</mn></math>'><span><span><span>100</span></span></span></span> km s<span tabindex="0" role="presentation" data-mathml='<math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mi></mi><mrow class="MJX-TeXAtom-ORD"><mo>−</mo><mn>1</mn></mrow></msup></math>'><span><span><span><span></span><span><span><span>−</span><span>1</span></span></span></span></span></span></span>. The differences are significant among the numerical results with different resolutions, which indicate that the realistic magnetic diffusivity is crucial to reveal the fine structures and realistic plasmas heating in these reconnection events. Our results also show that the reconnection heating contributed by ambipolar diffusion in the low chromosphere around the temperature minimum region is not efficient.</p>

Test particle acceleration in resistive torsional fan magnetic reconnection using laboratory plasma parameters

2021 ◽  
Vol 87 (6) ◽  
Author(s):  
D.L. Chesny ◽  
N.B. Orange ◽  
K.W. Hatfield
Keyword(s):  
Particle Acceleration ◽  
Magnetic Reconnection ◽  
Three Dimensional ◽  
Laboratory Plasma ◽  
Plasma Parameters ◽  
Astrophysical Plasmas ◽  
Magnetic Field Topology ◽  
Reconnection Region ◽  
Fundamental Process ◽  
Technology Applications

Particle acceleration via magnetic reconnection is a fundamental process in astrophysical plasmas. Experimental architectures are able to confirm a wide variety of particle dynamics following the two-dimensional Sweet–Parker model, but are limited in their reproduction of the fan-spine magnetic field topology about three-dimensional (3-D) null points. Specifically, there is not yet an experiment featuring driven 3-D torsional magnetic reconnection. To move in this direction, this paper expands on recent work toward the design of an experimental infrastructure for inducing 3-D torsional fan reconnection by predicting feasible particle acceleration profiles. Solutions to the steady-state, kinematic, resistive magnetohydrodynamic equations are used to numerically calculate particle trajectories from a localized resistivity profile using well-understood laboratory plasma parameters. We confine a thin, 10 eV helium sheath following the snowplough model into the region of this localized resistivity and find that it is accelerated to energies of ${\approx }2$ keV. This sheath is rapidly accelerated and focused along the spine axis propagating a few centimetres from the reconnection region. These dynamics suggest a novel architecture that may hold promise for future experiments studying solar coronal particle acceleration and for technology applications such as spacecraft propulsion.

scholarly journals Reflection of Fast Magnetosonic Waves near a Magnetic Reconnection Region

2018 ◽  
Vol 860 (2) ◽  
pp. 138 ◽  
Author(s):  
E. Provornikova ◽  
J. M. Laming ◽  
V. S. Lukin
Keyword(s):  
Magnetic Reconnection ◽  
Reconnection Region
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