Figures depicting the tendency of the B4 field to split into two flux ropes of opposing sign. Panels a)−c) the core field shown in Figs. 10a−f as viewed from the side. Panels d)−f) local twisting distributions L_f(x,y) of the B4 field for a simulation, whose core field lines are shown in panels g)−i), and whose maximum field strength is comparable to that of the background field (the flux rope of the field in panels a)−c) is a factor 3 stronger than in panels g)−i)).