Dynamical processes at the vertical current sheet behind an erupting flux rope

We report in this paper a solar eruptive event, in which a vertical current sheet (VCS) is observed in the wake of an erupting flux rope in the Solar Dynamic Observatory (SDO)/Atmospheric Imaging Assembly (AIA) 131 A passband. The VCS is first detected following the impulsive acceleration of the erupting flux rope but prior to the onset of a non-thermal hard X-ray (HXR)/microwave burst, with plasma blobs moving upwards at speeds up to 1400 km s(-1) along the sheet. The timing suggests that the VCS with plasma blobs might not be the primary accelerator for non-thermal electrons emitting HXRs/microwaves. The initial, slow acceleration of the erupting structure is associated with the slow elevation of a thermal looptop HXR source and the subsequent, impulsive acceleration is associated with the downward motion of the looptop source. We find that the plasma blobs moving downwards within the VCS into the cusp region and the flare loops retracting from the cusp region make a continuous process, with the former apparently initiating the latter, which provides a 3D perspective on reconnections at the VCS. We also identify a dark void moving within the VCS towards the flare arcade, which suggests that dark voids in supra-arcade downflows are of the same origin as plasma blobs within the VCS.