Upper panel: Evolution of the current j_z (in units of 10⁻¹⁰ G cm⁻¹) for case 1. Bottom panel: Evolution of B_z (in units of G) within the MFR. The initial time is depicted in the first panel, t = 5000 s in second panel, t = 16 000 s in third panel, and t = 17 000 s in the last panel. The black lines represent the projection of the magnetic field lines into the xy-plane. An associated movie is available online.