Fig. 7.

The normalized density of the high energy H⁺ ions on a spherical shell with radius r = 2.8R_M from the center of Mars (which is approximately the distance at which the Phobos-2 spacecraft measurements were made while following circular orbits). The flow lines are as shown in Fig. 6 and the run is a nominal one. The energies of the H⁺ ions are (a) 50 keV, (b) 200 keV, (c) 600 keV and (d) 3.2 MeV. The view is from the tail toward the Sun. Note how the size of the magnetic shadow (the dark blue region) decreases with increasing energy.