Energetic electrons have frequently been observed in small‐scale flux ropes. However, whether these energetic electrons were energized directly within the flux rope or not is unknown. In this paper, we present concrete evidence provided by the Magnetospheric Multiscale mission that a secondary flux rope provided strong acceleration for electrons expelled by the reconnection X line. We find that the energetic electron fluxes inside the ion‐scale flux rope were larger than those outside the flux rope. Electrons were adiabatically accelerated by betatron and Fermi mechanisms inside the flux rope. The highest energy electrons (>100 keV) were produced by betatron acceleration, whereas Fermi acceleration was unable to accelerate the electrons to high energy probably due to the finite distance of the acceleration region along the field‐aligned direction. These results confirm the essential role of ion‐scale flux ropes in producing energetic electrons.

Magnetic reconnection and turbulence are the two most important energy dissipation processes in plasma. These two processes intertwine with each other and play important roles in their respective dynamic evolution. Here, we present the first evidence that secondary reconnections occur in the turbulent outflow driven by a primary reconnection in the Earth's magnetotail. We have identified 14 secondary reconnections in a large number of current filaments in the turbulent outflow, which persisted for about one and half an hour. Most of these secondary reconnections were electron‐only reconnection that has recently been discovered in the magnetosheath. These secondary reconnections entangled the magnetic field lines and dissipated the magnetic energy in the outflow region far away from the primary X line.

It has been proposed that, in the near‐Earth magnetotail, earthward propagating flux ropes can merge with the Earth's dipole magnetic field and dissipate its magnetic energy. However, the reconnection diffusion region related to this process has not been identified. Here we report the first in situ observation of magnetic reconnection between an earthward propagating flux rope and the closed magnetic field lines connecting to Earth. Magnetospheric Multiscale (MMS) spacecraft crossed a vertical current sheet between the leading edge of the flux rope (negative Bz) and the geomagnetic field (positive Bz). The subion‐scale current sheet, super‐Alfvénic electron outflow, Hall magnetic and electric field, conversion of magnetic energy to plasma energy (J·E > 0), and magnetic null were observed during the crossing. All the above signatures indicate that MMS detected the reconnection diffusion region. This result is also relevant to other planets with intrinsic magnetosphere.