An Intrinsically Three-Dimensional Reconnection Process in Near-Earth Plasma Sheet*

A magnetic reconnection process in the near-Earth plasma sheet has been revealed to be intrinsically three-dimensional both geometrically and dynamically despite the spatial invariance of the original current sheet in the equilibrium current direction. Such a reconnection process is induced by the nonlinear development of an ideal MHD ballooning instability that leads to the appearance of quasi-separatrix layers in a generalized Harris sheet. The spatial distribution and structure of these quasi-separatrix layers, as well as their temporal evolution, indicate that the associated magnetic reconnection can only occur in the three-dimensional geometry which is irreducible to a two-dimensional reconnection process. *Supported by National Natural Science Foundation of China Grant No. 41474143.