Regular magnetic field generation in the ring for various values of d (2d is the width of ring) and dynamo numbers D. The upper panel shows the magnetic field for t = 10¹⁰yr for D = 20; the middle panel the same for D = 50. The solid curves are for a ring with d = 1 kpc, the dashed curve d = 1.5 kpc, and the dot-dashed curve is for d = 2 kpc. The lower panel shows the equipartition field B^∗ (which is determined by the kinetic energy of the turbulent gas) vs. radius for a representative case with L = 5 kpc, d = 1 kpc.