2D maps B(x, y) showing the result of the Bifrost runs for the first harmonic at the initial time (t = 0; τ_d = 1; upper panel) and at the end of the run (t = 4.8 × 10³; τ_d = 5.3 × 10⁴; lower panel). In the figure, the results for the case with the lowest resolution, n_x = n_y = 512, are presented. The decrease of the field strength with time can be clearly appreciated through the colour bar scales.