Evolution of clustered magnetic nulls in a turbulent-like reconnection region in the magnetotail

Magnetic null points and flux ropes play important roles in the three-dimensional process of magnetic reconnection. In this study, a cluster of null points are reconstructed in the reconnection region in the magnetotail by applying a fitting-reconstruction method to measurements from the Cluster mission. The number of reconstructed null points varies rapidly, presenting a turbulent-like evolution of the magnetic structure. The electron density and the flux of the accelerated electrons were enhanced in this turbulent-like region. During this unstable reconnection process, a B–A_s–B null structure was formed, showing flux rope features and resembling a secondary island in the observation.