Study of three-dimensional plasmoid dynamics by the spontaneous fast reconnection model: effects of dawn–dusk magnetic field Original Research Article

The dawn–dusk magnetic field component (Bz) in the plasmoid resulting of magnetic reconnections have been observed GEOTAIL satellite. We have studied the effects by Bz component in the reconnection in geomagnetotail. This paper present the results of computer simulation about them. Our recent simulation apply the spontaneous fast reconnection model to the three-dimensional (3-D) plasmoid dynamics. Previous our original 3-D computational region (the first quadrant) is extended to the second quadrant and axis symmetry boundary conditions are used. Then, various initial values of dawn–dusk magnetic field component Bz can be possibly assumed. As a result in all our simulation cases: (1) a large-scale plasmoid evolves, and (2) it propagates down to the geomagnetic tail, (3) slow shocks and finite amplitude intermediate waves simultaneously stand along the resulting plasmoid boundary layer. We also found that in the plasmoid where north–south magnetic field component (By) changes its sign, Bz also has a considerably big value, Which is consistent with the satellite observation result. We propose that the spontaneous fast reconnection mechanism could be most applicable to substorms.