Upper panel: regular magnetic field generation for various densities in the gap and the seed field in the inner disc. The upper panel shows the magnetic field at t = 10¹⁰yr for D = 20; the middle panel gives the same for D = 50. The solid curve shows ρ_gap = 10^-1ρ₀, the dashed curve ρ_gap = 10^-2ρ₀, and the dot-dashed curve ρ_gap = 10^-3ρ₀. R = 5 kpc, L = 2 kpc, d = 1 kpc. Without a ring the outer maximum in B is absent, and B continues to decline with radius. Lower panel: the dependence of pitch angle p = tan^-1(B_r/B_φ) on radius.