Fast reconnection evolution in an arcadelike magnetic loop structure

In the previous three-dimensional (3D) studies, the fast reconnection mechanism builds up in a narrow extent in the sheet current (z) direction, leading to a compact flare loop. In the present study, the 3D fast reconnection is allowed to evolve in a wide extent in the z direction and hence to proceed in a large arcadelike magnetic loop structure. Magnetic reconnection is initiated by a reconnection disturbance with a nonuniformity periodic in the z direction. According to different magnitudes of the initial disturbance in the z direction, magnetic reconnection is triggered in different manners and the resulting 3D fast reconnection evolution leads to the corresponding flare loop structures. When the z-directional nonuniformity is relatively small, the fast reconnection evolution extends with time in the z direction, leading to evolution of a large arcadelike flare loop, where the temperature is distinctly enhanced in the shape of two ribbons in the loop footpoint. On the other hand, when the disturbance nonuniformity is large, the fast reconnection evolution becomes less effective and compact flare loops tend to be formed isolated.