scholarly journals Interaction of multiple magnetic islands in a long current sheet: Two-fluid simulations

2010 ◽  
Vol 37 (2) ◽  
pp. n/a-n/a ◽  
Author(s):  
T. K. M. Nakamura ◽  
M. Fujimoto ◽  
H. Sekiya
Keyword(s):  
Current Sheet ◽  
Magnetic Islands ◽  
Two Fluid

Obliquely propagating generalized lower-hybrid drift instability with nonlocal two-fluid theory in current sheet equilibrium

2010 ◽  
Vol 17 (10) ◽  
pp. 102102 ◽  
Author(s):  
Dandan Zou ◽  
Weihong Yang ◽  
Yinhua Chen ◽  
P. H. Yoon
Keyword(s):  
Current Sheet ◽  
Lower Hybrid ◽  
Fluid Theory ◽  
Drift Instability ◽  
Two Fluid

scholarly journals A two-fluid study of oblique tearing modes in a force-free current sheet

2016 ◽  
Vol 23 (1) ◽  
pp. 012112 ◽  
Author(s):  
Cihan Akçay ◽  
William Daughton ◽  
Vyacheslav S. Lukin ◽  
Yi-Hsin Liu
Keyword(s):  
Current Sheet ◽  
Tearing Modes ◽  
Free Current ◽  
Two Fluid

scholarly journals Collapse of the neutral current sheet and reconnection at micro-scales

2008 ◽  
Vol 74 (2) ◽  
pp. 215-232 ◽  
Author(s):  
I. F. SHAIKHISLAMOV
Keyword(s):  
Current Sheet ◽  
Large Scale ◽  
Numerical Solutions ◽  
Neutral Current ◽  
Static Solution ◽  
New Process ◽  
Maximum Current ◽  
Nonlinear Static ◽  
Field Lines ◽  
Two Fluid

AbstractReconnection physics at micro-scales is investigated in an electron magnetohydrodynamics frame. A new process of collapse of the neutral current sheet is demonstrated by means of analytical and numerical solutions. It shows how at scales smaller than ion inertia length a compression of the sheet triggers an explosive evolution of current perturbation. Collapse results in the formation of a intense sub-sheet and then an X-point structure embedded into the equilibrium sheet. Hall currents associated with this structure support high reconnection rates. Nonlinear static solution at scales of the electron skin reveals that electron inertia and small viscosity provide an efficient mechanism of field lines breaking. The reconnection rate does not depend on the actual value of viscosity, while the maximum current is found to be restricted even for space plasmas with extremely rare collisions. The results obtained are verified by a two-fluid large-scale numerical simulation.

Structure of a singly ionizing current sheet propagating in a low density gas

1970 ◽  
Vol 48 (15) ◽  
pp. 1769-1780 ◽  
Author(s):  
G. J. Pert
Keyword(s):  
Steady State ◽  
Current Sheet ◽  
Electric Fields ◽  
Mean Free Path ◽  
Transverse Magnetic ◽  
Low Density ◽  
Free Model ◽  
Ionization Region ◽  
Electron Mean Free Path ◽  
Two Fluid

The structure of a singly ionizing current sheet is examined under steady-state conditions. Convergent solutions are only found in the presence of ambient transverse magnetic and electric fields. A collision-free model is used to approximate to the ionization region in the front. This solution is cut off at the electron mean free path and matched to a collision-dominated magnetohydrodynamic two-fluid calculation for the back of the sheet. The conditions for the establishment of a steady state are examined for these solutions.

Acceleration of ions in a current sheet with magnetic islands

1988 ◽  
Vol 129 (5-6) ◽  
pp. 326-328 ◽  
Author(s):  
A.T. Altyntsev ◽  
N.V. Lebedev ◽  
N.A. Strokin
Keyword(s):  
Current Sheet ◽  
Magnetic Islands ◽  
A Current

Resistive tearing-mode instability in a magnetic-field-reversing current sheet with coplanar viscous stagnation-point flow

1996 ◽  
Vol 56 (2) ◽  
pp. 265-284 ◽  
Author(s):  
Justin T. C. Ip ◽  
Bengt U. Ö. Sonnerup
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Stagnation Point ◽  
Linear Growth ◽  
Field Configuration ◽  
Stagnation Point Flow ◽  
Magnetic Islands ◽  
Tearing Mode ◽  
Mode Instability ◽  
Simulation Results

The tearing-mode instability of a magnetic-field-reversing current sheet in the presence of coplanar incompressible stagnation-point flow is examined. The unperturbed equilibrium state is an exact solution of the steady-state, dissipative, incompressible magnetohydrodynamic equations; thus the analysis is valid even for small viscous and resistive Lundquist numbers Sν and Sη. The instability problem has no known analytical solution; for this reason, it is studied numerically by use of a finite-element method. Simulation results indicate stability for sufficiently small values of Sν or Sη and instability for large values. The boundary separating stable and unstable regions in the (Sν, Sη) plane is located. In the unstable regime, the simulation results show formation and subsequent convection of magnetic islands along the current sheet at about 80% of the unperturbed outflow flow speed, on average. Stretching and pinching of convecting magnetic islands are also observed. The results show the occurrence of multiple X-line reconnection at the centre of the current sheet (x = 0). Small-scale structures of vorticity and current density near the X-point reconnection sites are found to be qualitatively consistent with results obtained by Matthaeus. Normalized global linear growth rates are found to obey the approximate power law, within the ranges 20 ≦ Sν ≦ 70 and 200 ≦ Sη 1000. At least for Sν ≦ 1000, the number of magnetic islands is found to be nearly independent of Sν indicating the existence of a narrow band of dominant wavelengths in this range. The stretching of magnetic islands, which is present in this coplanar flow and field configuration, but not in the perpendicular flow and field configuration examined by Phan and Sonnerup, causes a substantial decrease in linear growth rate relative to that obtained by those authors. The stability curves obtained are qualitatively similar in both analyses, but the stable region is much larger for coplanar flow and field. Unlike most simulations of the tearing mode, no symmetry conditions are imposed on the perturbations; nevertheless, they develop in a symmetric manner.

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