Three-dimensional evolution of the fast reconnection mechanism in a sheared current sheet

2010 ◽  
Vol 17 (3) ◽  
pp. 032313 ◽  
Author(s):  
M. Ugai
Keyword(s):  
Current Sheet ◽  
Three Dimensional ◽  
Fast Reconnection

Computer modelling of three-dimensional dynamics of fast reconnection

1991 ◽  
Vol 45 (2) ◽  
pp. 251-266 ◽  
Author(s):  
M. Ugai
Keyword(s):  
Current Sheet ◽  
Computer Modelling ◽  
Neutral Line ◽  
Current System ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Reconnection Process ◽  
Reconnection Region ◽  
Set Up ◽  
Fast Reconnection

Computer simulations are used to investigate the basic three-dimensional structure of the fast reconnection mechanism spontaneously developing from a long current sheet. It is shown that if three-dimensional effects (∂sol;∂z ≠ 0) are not so strong, a locally enhanced resistivity results in current-sheet thinning, and a fast reconnection process, involving switch-off shocks, is eventually set up in a region limited in the z direction. The fast reconnection process near the z = 0 plane becomes quasi-steady and two-dimensional (∂/∂z = 0), so that the well-known Petschek mechanism is fully applicable. Distinct plasma rarefaction occurs inside the fast reconnection region, so that fast-mode expansion may propagate in the z direction, and the resulting inflow velocity uz takes the magnetic field into the fast reconnection region and contracts the latter. The global current system undergoes drastic changes during the fast-reconnection development. The current flow, initially directed in the z direction, first converges towards the neutral line, and is then largely deflected away from this line in the inner reconnection region.

scholarly journals Magnetic field structure of large-scale plasmoid generated by the fast reconnection mechanism in a sheared current sheet

2010 ◽  
Vol 28 (8) ◽  
pp. 1511-1521 ◽  
Author(s):  
M. Ugai
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Large Scale ◽  
Field Component ◽  
Three Dimensional ◽  
Magnetized Plasma ◽  
The North ◽  
Magnetic Field Region ◽  
Field Lines ◽  
Fast Reconnection

Abstract. On the basis of the spontaneous fast reconnection model, three-dimensional magnetic field profiles associated with a large-scale plasmoid propagating along the antiparallel magnetic fields are studied in the general sheared current sheet system. The plasmoid is generated ahead of the fast reconnection jet as a result of distinct compression of the magnetized plasma. Inside the plasmoid, the sheared (east-west) field component has the peak value at the plasmoid center located at x=XC, where the north-south field component changes its sign. The plasmoid center corresponds to the so-called contact discontinuity that bounds the reconnected field lines in x<XC and the field lines without reconnection in x>XC. Hence, contray to the conventional prediction, the reconnected sheared field lines in x<XC are not spiral or helical, since they cannot be topologically connected to the field lines in x>XC. It is demonstrated that the resulting profiles of magnetic field components inside the plasmoid are, in principle, consistent with satellite observations. In the ambient magnetic field region outside the plasmoid too, the magnetic field profiles are in good agreement with the well-known observations of traveling compression regions (TCRs).

scholarly journals Numerical study of the reconnection process between magnetic cloud and heliospheric current sheet

2018 ◽  
Vol 619 ◽  
pp. A82
Author(s):  
Man Zhang ◽  
Yu Fen Zhou ◽  
Xue Shang Feng ◽  
Bo Li ◽  
Ming Xiong
Keyword(s):  
Magnetic Reconnection ◽  
Current Sheet ◽  
Dynamic Process ◽  
Large Scale ◽  
Magnetic Cloud ◽  
Numerical Study ◽  
Three Dimensional ◽  
Heliospheric Current Sheet ◽  
Reconnection Process ◽  
Magnetic Filed

In this paper, we have used a three-dimensional numerical magnetohydrodynamics model to study the reconnection process between magnetic cloud and heliospheric current sheet. Within a steady-state heliospheric model that gives a reasonable large-scale structure of the solar wind near solar minimum, we injected a spherical plasmoid to mimic a magnetic cloud. When the magnetic cloud moves to the heliospheric current sheet, the dynamic process causes the current sheet to become gradually thinner and the magnetic reconnection begin. The numerical simulation can reproduce the basic characteristics of the magnetic reconnection, such as the correlated/anticorrelated signatures in V and B passing a reconnection exhaust. Depending on the initial magnetic helicity of the cloud, magnetic reconnection occurs at points along the boundary of the two systems where antiparallel field lines are forced together. We find the magnetic filed and velocity in the MC have a effect on the reconnection rate, and the magnitude of velocity can also effect the beginning time of reconnection. These results are helpful in understanding and identifying the dynamic process occurring between the magnetic cloud and the heliospheric current sheet.

scholarly journals 3D turbulent reconnection driven current-sheet dynamics: solar applications

2010 ◽  
Vol 6 (S274) ◽  
pp. 458-460
Author(s):  
Lapo Bettarini ◽  
Giovanni Lapenta
Keyword(s):  
Current Sheet ◽  
Characteristic Time ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Anomalous Effect ◽  
Instability Modes ◽  
Diffusive Dynamics ◽  
Three Dimensional Configuration ◽  
A Current ◽  
Dimensional Picture

AbstractWe provide a complete three-dimensional picture of the reconnecting dynamics of a current-sheet. Recently, a two-dimensional non-steady reconnection dynamics has been proved to occur without the presence of any anomalous effect (Lapenta, 2008, Skender & Lapenta, 2010, Bettarini & Lapenta, 2010) but such a picture must be confirmed in a full three-dimensional configuration wherein all instability modes are allowed to drive the evolution of the system, i.e. to sustain a reconnection dynamics or to push the system along a different instability path. Here we propose a full-space analysis allowing us to determine the longitudinal and, possibly, the transversal modes driving the different current-sheet disruption regimes, the corresponding characteristic time-scales and to study system's instability space- parameter (plasma beta, Lundquist and Reynolds numbers, system's aspect ratio). The conditions leading to an explosive evolution rather then to a diffusive dynamics as well as the details of the reconnection inflow/outflow regime at the disruption phase are determined. Such system embedded in a solar-like environment and undergoing a non-steady reconnection evolution may determine the formation both of jets and waves influencing the dynamics and energetic of the upper layers and of characteristic down-flows as observed in the low solar atmosphere.

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