scholarly journals A tailward moving current sheet normal magnetic field front followed by an earthward moving dipolarization front

2014 ◽  
Vol 119 (7) ◽  
pp. 5316-5327 ◽  
Author(s):  
K.-J. Hwang ◽  
M. L. Goldstein ◽  
T. E. Moore ◽  
B. M. Walsh ◽  
D. G. Baishev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Dipolarization Front ◽  
Normal Magnetic Field

scholarly journals MHD aspect of current sheet oscillations related to magnetic field gradients

2009 ◽  
Vol 27 (1) ◽  
pp. 417-425 ◽  
Author(s):  
N. V. Erkaev ◽  
V. S. Semenov ◽  
I. V. Kubyshkin ◽  
M. V. Kubyshkina ◽  
H. K. Biernat
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Field Component ◽  
Short Wave ◽  
Magnetic Field Component ◽  
Wave Number ◽  
Dispersion Function ◽  
Small Scale ◽  
Magnetic Field Gradients ◽  
Normal Magnetic Field

Abstract. One-fluid ideal MHD model is applied for description of current sheet flapping disturbances appearing due to a gradient of the normal magnetic field component. The wave modes are studied which are associated to the flapping waves observed in the Earth's magnetotail current sheet. In a linear approximation, solutions are obtained for model profiles of the electric current and plasma densities across the current sheet, which are described by hyperbolic functions. The flapping eigenfrequency is found as a function of wave number. For the Earth's magnetotail conditions, the estimated wave group speed is of the order of a few tens kilometers per second. The current sheet can be stable or unstable in dependence on the direction of the gradient of the normal magnetic field component. The obtained dispersion function is used for calculation of the flapping wave disturbances, which are produced by the given initial Gaussian perturbation at the center of the current sheet and propagating towards the flanks. The propagating flapping pulse has a smooth leading front, and a small scale oscillating trailing front, because the short wave oscillations propagate much slower than the long wave ones.

Tearing instability inside a 2D current sheet with a normal magnetic field

2021 ◽  
Author(s):  
Chen Shi ◽  
Anton Artemyev ◽  
Marco Velli ◽  
Anna Tenerani
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Normal Component ◽  
Field Energy ◽  
Tearing Mode ◽  
Magnetic Field Energy ◽  
Tearing Instability ◽  
The Magnetic Field ◽  
Normal Magnetic Field

<p>Magnetic reconnection converts the magnetic field energy into thermal and kinetic energies of the plasma. This process usually happens at extremely fast speed and is therefore believed to be a fundamental mechanism to explain various explosive phenomena such as coronal mass ejections and planetary magnetospheric storms. How magnetic reconnection is triggered from the large magnetohydrodynamic (MHD) scales remains an open question, with some theoretical and numerical studies showing the tearing instability to be involved. Observations in the Earth’s magnetotail and near the magnetopause show that a finite normal magnetic field is usually present inside the reconnecting current sheet. Besides, such a normal field may also exist in the solar corona. However, how this normal magnetic field modifies the tearing instability is not thoroughly studied. Here we discuss the linear tearing instability inside a two-dimensional current sheet with a normal component of magnetic field where the magnetic tension force is balanced by ion flows parallel and anti-parallel to the magnetic field. We solve the dispersion relation of the tearing mode with wave vector parallel to the reconnecting magnetic field. Our results confirm that the finite normal magnetic field stabilizes the tearing mode and makes the mode oscillatory instead of purely growing.</p>

Asymmetric configurations of a thin current sheet with a constant normal magnetic field component

2009 ◽  
Vol 35 (1) ◽  
pp. 76-83 ◽  
Author(s):  
O. V. Mingalev ◽  
I. V. Mingalev ◽  
Kh. V. Malova ◽  
L. M. Zelenyi ◽  
A. V. Artem’ev
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Field Component ◽  
Magnetic Field Component ◽  
Thin Current Sheet ◽  
Normal Magnetic Field

scholarly journals Solar wind and substorm excitation of the wavy current sheet

2009 ◽  
Vol 27 (6) ◽  
pp. 2457-2474 ◽  
Author(s):  
C. Forsyth ◽  
M. Lester ◽  
R. C. Fear ◽  
E. Lucek ◽  
I. Dandouras ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Current Sheet ◽  
Pressure Pulse ◽  
Wind Pressure ◽  
Expansion Velocity ◽  
Solar Wind Pressure ◽  
Wave Models ◽  
Best Fit ◽  
The Magnetic Field

Abstract. Following a solar wind pressure pulse on 3 August 2001, GOES 8, GOES 10, Cluster and Polar observed dipolarizations of the magnetic field, accompanied by an eastward expansion of the aurora observed by IMAGE, indicating the occurrence of two substorms. Prior to the first substorm, the motion of the plasma sheet with respect to Cluster was in the ZGSM direction. Observations following the substorms show the occurrence of current sheet waves moving predominantly in the −YGSM direction. Following the second substorm, the current sheet waves caused multiple current sheet crossings of the Cluster spacecraft, previously studied by Zhang et al. (2002). We further this study to show that the velocity of the current sheet waves was similar to the expansion velocity of the substorm aurora and the expansion of the dipolarization regions in the magnetotail. Furthermore, we compare these results with the current sheet wave models of Golovchanskaya and Maltsev (2005) and Erkaev et al. (2008). We find that the Erkaev et al. (2008) model gives the best fit to the observations.

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