Division of Magnetic Flux Rope via Magnetic Reconnection Observed in the Magnetotail

Using high‐resolution data from Magnetospheric Multiscale (MMS) mission, we report an intense current layer at the center of a flux rope (FR) in the magnetotail. The intense current layer is caused by the compression of the ion bulk flows at the center of a FR rather than two interlaced flux tubes reported at the magnetopause previously. The intense current layer has been identified as an electron diffusion region of the magnetic reconnection, and the hall magnetic field generated by magnetic reconnection makes the FR show crater‐shaped. The reconnecting current layer is supported by the poloidal magnetic field of the FR, and it is dividing the FR into two secondary FRs. The observations suggest that magnetic FR can be compressed easily to excite instability inside it as it is propagating in the magnetotail current sheet, thus changing its magnetic topology. Plain Language Summary Magnetic flux ropes (FRs) consist of a poloidal magnetic field and an axial magnetic field component and are always described as helical magnetic field structures. The FRs play an important role in particle acceleration, magnetic flux transportation, and the evolution of reconnection. Recently, with high‐resolution magnetic field and plasma moments measurements, it is found that the interior of the FR is active, and a lot of processes could occur therein. In this work, we report a FR embedded in an unstable tailward plasma flow in the magnetotail. An ongoing reconnection current layer is observed at the center of the FR. The reconnecting current layer could change the magnetic field topology of the initial FR and divide the initial FR into two secondary FRs. Key Points An electron diffusion region of reconnection is observed at the center of the flux rope (FR) in the magnetotail The reconnecting current layer can change the magnetic field topology inside the FR and divide it into two secondary FRs The Hall magnetic field inside the reconnecting current layer leads to the crater‐shaped magnetic field magnitude within the FR