MHD simulations of fast reconnection spontaneously developing in a current sheet

1988 ◽  
Vol 49 (1) ◽  
pp. 185-192 ◽  
Author(s):  
M. Ugai
1998 ◽  
Vol 188 ◽  
pp. 207-208
Author(s):  
T. Magara ◽  
K. Shibata

In this study, we perform 2.5-dimensional MHD simulations and clarify the role of perpendicular magnetic fields (which are perpendicular to the 2D plane) in a preflare current sheet of solar flares. At the first stage, a current sheet formed within a coronal magnetic structure is filled with the perpendicular fields (force-free structure). Then this sheet begins to be dissipated through the tearing instability under a uniform resistivity. As the instability proceeds, the distribution of the perpendicular fields vary in such a way that most of them gather around O-point (magnetic island) instead of X-point. Therefore, the magnetic pressure of these fields weaken in the vicinity of X-point so that they no longer suppress the inflows toward this point. These flows then make the current sheet thinner and thinner, which implies that the current density around X-point becomes high enough to cause an anomalous resistivity whose value is much larger than that of the normal collisional resistivity. In this way, the transition from a uniform resistivity to a locally-enhanced one occurs, which can make the violent energy release observed in solar flares.


2002 ◽  
Vol 68 (1) ◽  
pp. 53-58
Author(s):  
MANUEL NÚÑEZ

Magnetic reconnection is one of the most efficient ways of transforming magnetic into kinetic and thermal energies. We prove a general identity relating the energy transfer in a neighborhood of a current sheet, where reconnection is assumed to occur. With some reasonable hypotheses regarding the geometry of stream and field lines, we prove that for a constant rate of transformation of magnetic energy, the width of the current sheet must grow with the plasma conductivity. Hence an enhanced diffusivity seems necessary for certain classical models of fast reconnection to work.


2016 ◽  
Vol 10 (7) ◽  
pp. 709-718
Author(s):  
Honglei Wang ◽  
Kunde Yang ◽  
Kun Zheng ◽  
Yixin Yang ◽  
Yuanliang Ma

2017 ◽  
Vol 52 (4) ◽  
pp. 463-467 ◽  
Author(s):  
S. D. Kovalevskaya
Keyword(s):  

2008 ◽  
Vol 41 (10) ◽  
pp. 1630-1642 ◽  
Author(s):  
Mostafa El-Alaoui ◽  
Maha Ashour-Abdalla ◽  
Jean Michel Bosqued ◽  
Robert L. Richard

2021 ◽  
Author(s):  
Zhi-Yang Liu ◽  
Qiu-Gang Zong ◽  
Michel Blanc

<p>Jupiter's magnetosphere contains a current sheet of huge size near its equator. The current sheet not only mediates the global mass and energy cycles of Jupiter's magnetosphere, but also provides an occurring place for many localized dynamic processes, such as reconnection and wave-particle interaction. To correctly evaluate its role in these processes, a statistical description of the current sheet is required. To this end, here we conduct statistics on Jupiter's current sheet, with four-year Juno data recorded in the 20-100 Jupiter radii, post-midnight magnetosphere. The results suggest a thin current sheet whose thickness is comparable with the gyro-radius of dominant ions. Magnetic fields in the current sheet decrease in power-law with increasing radial distances. At fixed energy, the flux of electrons and protons increases with decreasing radial distances. On the other hand, at fixed radial distances, the flux decreases in power-law with increasing energy. The flux also varies with the distances to the current sheet center. The corresponding relationship can be well described by Gaussian functions peaking at the current sheet center. In addition, the statistics show the flux of oxygen- and sulfur-group ions is comparable with the flux of protons at the same energy and radial distances, indicating the non-negligible effects of heavy ions on current sheet dynamics. From these results, a statistical model of Jupiter's current sheet is constructed, which provides us with a start point of understanding the dynamics of the whole Jupiter's magnetosphere.</p>


2006 ◽  
Vol 458 (1) ◽  
pp. 307-315
Author(s):  
G. Fruit ◽  
I. J. D. Craig
Keyword(s):  

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