Diagram of the field morphology of the half-torus model described in Sect. 3. This diagram corresponds to the test model presented in Sect. 5.1. The dotted line corresponds to the torus axis with a field strength B₀ = 3000 G. The light green surface shows the tube isosurface defined by a small radius a = 4.5 and large radius R = 12, both in pixel units. The x_c and y_c parameters correspond to the torus central position in pixel units in the xy−plane. ϕ is the tube tilt angle with respect to the x−axis. The photospheric plane is located at a height d = 6.5 with respect to the torus center. The red and blue contours over this plane indicates the projection of the torus field in the z−direction with a field strength of 500 G and −500 G, respectively.