Cuts perpendicular to the loop axis at different distances to the photospheric layer through the structure shown in Fig. 2. From left to right: Velocity perpendicular to the loop axis, density, axial component of the Poynting flux, axial component of the Lorentz force, and X-ray emission. From the top to the bottom row, cuts are shown at values of the axial coordinate s of 1.3 Mm, 6 Mm, 10 Mm, and 20 Mm. The arrows show direction and magnitude of the velocity field. The units of the X-ray emission are . The center of the main vortex flow is marked with a star. The vortex center has been determined as the location of peak vorticity magnitude computed from the velocity field smoothed with a Gaussian with an FWHM of 500 km. For a discussion, see Sects. 3.1 and 4.1.