Large-scale magnetic field strengths for different models of the ionized gas component and initial conditions. The top panel shows the strength of the final magnetic fields (i.e. at 10 Gyr) for different amplitudes of the initial conditions: curves from bottom to top indicate B₀ = 10^-5 μG, B₀ = 10^-4 μG, and B₀ = 10^-3 μG. The middle panel shows the final field strengths for different distances of the peak of the initial field from the centre: curves from bottom to top show r₀ = 6 kpc, r₀ = 16 kpc, and r₀ = 20 kpc. The bottom panel shows the final magnetic field strengths for different models of the dynamo scaleheight: the solid curve corresponds to model 1, the dashed curve to model 2a, the dotted curve to model 2b.