Arrows display the initial Lorentz force in the plane z = 0.5 for the main experiment with initial current j_sep = 1.5. The pale-blue/pink lines indicate where the separatrix surfaces from the lower/upper nulls of the initial (dashed) and equilibrium (solid) magnetic fields intersect the plane. The arrows indicate the strength (by their size and colour) and direction of the Lorentz force in the plane. The length of the arrows has been normalised to the maximum value of | j × B | in the domain.