Tearing modes in the magnetopause current sheet

1983 ◽  
Vol 97 (2) ◽  
pp. 421-426 ◽  
Author(s):  
G. S. Lakhina ◽  
K. Schindler
Keyword(s):  
Current Sheet ◽  
Tearing Modes

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

Linear tearing modes of a forced current-sheet equilibrium

1990 ◽  
Vol 353 ◽  
pp. 658 ◽  
Author(s):  
Paulett C. Liewer ◽  
David G. Payne
Keyword(s):  
Current Sheet ◽  
Tearing Modes

scholarly journals Effect of guide field on three-dimensional electron shear flow instabilities in electron current sheets

2015 ◽  
Vol 81 (6) ◽  
Author(s):  
Neeraj Jain ◽  
Jörg Büchner
Keyword(s):  
Shear Flow ◽  
Current Sheet ◽  
Three Dimensional ◽  
Sheet Thickness ◽  
Electron Current ◽  
Tearing Mode ◽  
Current Sheets ◽  
Tearing Modes ◽  
Guide Field ◽  
Half Thickness

We examine, in the limit of electron plasma ${\it\beta}_{e}\ll 1$, the effect of an external guide field and current sheet thickness on the growth rates and nature of three-dimensional (3-D) unstable modes of an electron current sheet driven by electron shear flow. The growth rate of the fastest growing mode drops rapidly with current sheet thickness but increases slowly with the strength of the guide field. The fastest growing mode is tearing type only for thin current sheets (half-thickness ${\approx}d_{e}$, where $d_{e}=c/{\it\omega}_{pe}$ is the electron inertial length) and zero guide field. For finite guide field or thicker current sheets, the fastest growing mode is a non-tearing type. However, growth rates of the fastest 2-D tearing and 3-D non-tearing modes are comparable for thin current sheets ($d_{e}<\text{half thickness}<2\,d_{e}$) and small guide field (of the order of the asymptotic value of the component of magnetic field supporting the electron current sheet). It is shown that the general mode resonance conditions for tearing modes depend on the effective dissipation mechanism. The usual tearing mode resonance condition ($\boldsymbol{k}\boldsymbol{\cdot }\boldsymbol{B}_{0}=0$, $\boldsymbol{k}$ is the wavevector and $\boldsymbol{B}_{0}$ is the equilibrium magnetic field) can be recovered from the general resonance conditions in the limit of weak dissipation. The conditions (relating current sheet thickness, strength of the guide field and wavenumbers) for the non-existence of tearing mode are obtained from the general mode resonance conditions. We discuss the role of electron shear flow instabilities in magnetic reconnection.

Quasilinear saturation of forced current sheet tearing modes

1990 ◽  
Vol 17 (11) ◽  
pp. 2047-2050 ◽  
Author(s):  
Paulett C. Liewer ◽  
David G. Payne
Keyword(s):  
Current Sheet ◽  
Tearing Modes

Forced reconnexion by fast magnetosonic waves in a current sheet with stagnation-point flows

1983 ◽  
Vol 30 (1) ◽  
pp. 109-124 ◽  
Author(s):  
Jun-Ichi Sakai
Keyword(s):  
Current Sheet ◽  
Stagnation Point ◽  
Solar Flares ◽  
Ponderomotive Force ◽  
Magnetosonic Wave ◽  
Fast Wave ◽  
Tearing Mode ◽  
Tearing Modes ◽  
Tearing Instability ◽  
A Current

Forced reconnexion due to tearing modes driven by fast magnetosonic waves in a current sheet with stagnation-point flows is discussed. The current sheet with stagnation-point flows which is weakly unstable against tearing modes can be strongly destabilized by vortex motions due to the ponderomotive force of the fast magnetosonic wave. This forced tearing instability can be driven when the incident fast magnetosonic wave intensity, I, exceeds a critical value given by where is the Alfvén velocity, vg the group velocity of the fast wave, vo the background inflow velocity, l the thickness of the current sheet and k the wavenumber of the forced tearing mode. The growth rate is estimated. Applications to solar flares and magnetopause reconnexion processes are briefly discussed.

Resistive tearing-mode instability in a current sheet with equilibrium viscous stagnation-point flow

1991 ◽  
Vol 46 (3) ◽  
pp. 407-421 ◽  
Author(s):  
T. D. Phan ◽  
B. U.Ö. Sonnerup
Keyword(s):  
Growth Rate ◽  
Current Sheet ◽  
Stagnation Point ◽  
Solar Wind Plasma ◽  
Stagnation Point Flow ◽  
Growth Time ◽  
Tearing Mode ◽  
Long Wavelength ◽  
Tearing Modes ◽  
A Current

An analysis is presented of linear stability against tearing modes of a current sheet formed between two oppositely magnetized plasmas forced towards each other in two-dimensional steady stagnation-point flow. The velocity vector in this flow is confined to planes perpendicular to the reversing component of the magnetic field. The unperturbed state is an exact resistive and viscous equilibrium in which the resistive diffusion outwards from the current sheet is exactly balanced by the inward motion associated with the stagnation-point flow. Thus the behaviour of the tearing mode can be examined even when the resistive diffusion time is comparable to or smaller than the growth time of the instability. The linear ordinary differential equation describing the mode structure is integrated numerically. For large Lundquist number S and viscous Reynolds number Re the Furth-Killeen-Rosenbluth scaling of the growth rate is recovered with excellent accuracy. The influence of the stagnation-point flow on the tearing mode is as follows: (i) long-wavelength perturbations are stabilized so that the unstable regime falls between a short-wavelength and a long-wavelength marginal state; (ii) for sufficiently low Lundquist number (S < 12.25) the current sheet is completely stable to tearing-mode perturbations; (iii) the presence of high viscosity reduces the growth rate of the tearing instability. This effect is more important at small wavelength. Finally, application of the results from this study to the problem of solar-wind plasma flow past the earth's magnetosphere is briefly discussed.

On reconnexion experiments and their interpertation

1977 ◽  
Vol 18 (2) ◽  
pp. 257-272 ◽  
Author(s):  
P. J. Baum ◽  
A. Bratenahl
Keyword(s):  
Boundary Conditions ◽  
Current Sheet ◽  
Neutral Current ◽  
Theoretical Description ◽  
Constrained Systems ◽  
Tearing Mode ◽  
Current Sheets ◽  
Tearing Modes ◽  
Proper Role ◽  
Natural Boundary Conditions

A number of reconnexion concepts and experiments are briefly reviewed in order to re-examine the present interpretation of these experiments. In particular, we offer explanations as to why some experiments appear to develop Petschek modes, tearing modes, or netural current sheets. The explanations require an understanding of the proper role of magnetic Reynolds numbers, the limits of the frozen-in concept, and the importance of natural importance of natural boundary conditions. We find that netural current sheets usually from in experiments with highly symmetrical (and therefore unnatural) boundary conditions. The classical tearing mode develops from perturbations of a neutral current sheet. In less constrained geometries multiple neutral points may appear but the classical tearing mode theory needs modification to explain these cases rigorously. A Petschek mode develops in even less constrained systems although the theoretical description is highly idealized. We offer explanations as to why some experimenters appear to find neutral current sheets in quadrupole fields and examine the usefulness of concepts derived from neutral current sheet theory.

Global and local processes of thin current sheet formation during substorm growth phase

2021 ◽  
pp. 105671
Author(s):  
A. Runov ◽  
V. Angelopoulos ◽  
A.V. Artemyev ◽  
J.M. Weygand ◽  
S. Lu ◽  
...  
Keyword(s):  
Current Sheet ◽  
Growth Phase ◽  
Thin Current Sheet ◽  
Global And Local

Observational support for the current sheet catastrophe model of substorm current disruption

1992 ◽  
Vol 19 (16) ◽  
pp. 1635-1638 ◽  
Author(s):  
G. R. Burkhart ◽  
R. E. Lopez ◽  
P. B. Dusenbery ◽  
T. W. Speiser
Keyword(s):  
Current Sheet ◽  
Catastrophe Model ◽  
Current Disruption
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