Symmetric Magnetic Reconnection Research Articles

CRITICAL DIFFERENCES OF ASYMMETRIC MAGNETIC RECONNECTION FROM STANDARD MODELS

ABSTRACT We have clarified the structure of asymmetric magnetic reconnection in detail as the result of the spontaneous evolutionary process. The asymmetry is imposed as ratio k of the magnetic field strength in both sides of the initial current sheet (CS) in the isothermal equilibrium. The MHD simulation is carried out by the HLLD code for the long-term temporal evolution with very high spatial resolution. The resultant structure is drastically different from the symmetric case (e.g., the Petschek model) even for slight asymmetry k = 2. (1) The velocity distribution in the reconnection jet clearly shows a two-layered structure, i.e., the high-speed sub-layer in which the flow is almost field aligned and the acceleration sub-layer. (2) Higher beta side (HBS) plasma is caught in a lower beta side plasmoid. This suggests a new plasma mixing process in the reconnection events. (3) A new large strong fast shock in front of the plasmoid forms in the HBS. This can be a new particle acceleration site in the reconnection system. These critical properties that have not been reported in previous works suggest that we contribute to a better and more detailed knowledge of the reconnection of the standard model for the symmetric magnetic reconnection system.

Properties of the resistive instability in double current sheet systems with strong shear flows

The resistive instability in double current sheet (DCS) systems with shear flows are explored by using a magnetohydrodynamic simulation method. The results showed that the linear growth rate of the antisymmetric and symmetric magnetic reconnection modes depend on the relative vicinity of the two current sheets. When the shear flows are strong and have velocities near or larger than the local Alfvén speed, the growth of the antisymmetric mode resistive instability in DCS systems is further increased. It is also found that the growth rate of the resistive instability decreases as the plasma beta increases.