a) Magnetic field magnitude distribution inside a toroidal flux rope with practically circular cross section. The closed lines are cross sections of magnetic surfaces. The values of free parameters are M = 5, d₀ = 1, d₁ = 0., e₁ = 1.698, d₂ = 2.099, e₂ = 0., d₃ = 0., e₃ = 0.554, d₄ = 1.699, e₄ = 0., d₅ = 0., and e₅ = −0.841. b) Magnetic field magnitude distribution and magnetic surfaces of the field defined by the generating cylinder, which was used for the construction of the flux rope shown in panel a), i.e., the field (9)–(11). In contrast to panel a), they are shown in the whole field of view because the magnetic field from all space contributes to the solution displayed in panel a). The cross section of the generating cylinder is plotted by the dashed circle, and the tilde coordinates are the local coordinates defined in Fig. 1. The magnetic-field magnitude scale is the same, but the values of B_max are different and correspond to the maxima in the displayed fields in panels a) and b). The thick lines indicate magnetic surfaces on which the axial magnetic field is zero.