Run A3. From top to bottom: evolution of magnetic field |B| (a), velocity u_x (b) and u_y (c), and density ρ (d). For |B| and ρ, the fields’ decay with heliocentric distance has been compensated for better visualisation. The in-plane magnetic field is represented in panels (a-c) as constant-A_z black lines, whereas the outermost boundary of the pinch tracer is represented in panel (d) as a dashed white line. All the quantities are in code units.