Physical Implication of Two Types of Reconnection Electron Diffusion Regions With and Without Ion‐Coupling in the Magnetotail Current Sheet.

By comparing an electron‐only reconnection event with a traditional reconnection event observed in the magnetotail, we illustrate the differences between and similarities of the two events. The electron behaviors are very similar in both events, but intensities of the electron flows and temperature in the traditional reconnection are much stronger than those in the electron‐only reconnection. The Hall electric field in the traditional reconnection occurs on the ion‐scale and is deflected from the normal direction by the significant magnetic field reconnected, while this field varies on the electron‐scale and points to the middle plane in the electron‐only reconnection. The comparison indicates that the electrons are undergoing the same process in both events, and the electron‐only reconnection was prior to the traditional reconnection. The Hall electric field could control the form of reconnection: producing either electron‐only reconnection or traditional reconnection. Key Points: We illustrate the differences between and similarities of the electron‐only reconnection and the normal reconnectionThe electron reconnection was prior to the normal reconnectionThe Hall electric field and the reconnected magnetic field intensity could control the form of reconnection [ABSTRACT FROM AUTHOR]