Fig. 4: Simplified schematics showing the events within the tail current sheet leading to the eruption of the tail-wide plasmoid.
From: Magnetotail plasma eruptions driven by magnetic reconnection and kinetic instabilities
a, The situation within Fig. 1b, showing the two local reconnection regions Earthward and tailward of the dominant x line. Magnetic field topology is given, with ⊙ and ⊗ symbols representing outward and inward directions with respect to the plane and corresponding to Bz > 0 and Bz < 0, respectively. b, The situation within Fig. 1c, where the dusk flank local flux rope is mainly Earthward of the dominant x line. The flapping begins. c, The situation within Fig. 1d, where the flapping waves have evolved into the strong central fold in the noon–midnight meridional plane. The flux ropes have grown and moved tailwards and towards the centre of the plasma sheet. d, The situation within Fig. 1g, where the large tail-wide plasmoid has been formed from the two local flank flux ropes. Their merging in the centre current sheet was enabled by the current disruption within the central fold. In all panels, the position of the dominant x line is a result of a competition between two x lines. The one that is stronger diverts flow, and hence the global flow reversal changes position.
