The trajectories of mainly low-energy ionosphere ions injected near the polar cusp into the polar magnetosphere are presented for a model polar magnetosphere including the effects of convection electric fields and gravitation. The trajectories display the ion mass and energy differentiation which has been seen in recent satellite observations of low-energy ionospheric ions injected into the polar magnetosphere, and indicate that for reasonable ranges of injectrion energy, pitch angle and convection electric field: 1. Transport of low-energy 'polar cusp' 0+ to the ~1 Re altitude nightside auroral acceleration region is feasible; and 2. Preferential trapping of energetic 0+ relative to H+ and He+ energetic ions occur in the closed field line region of the magnetotail plasma sheet. Two interesting classes of polar region very low-energy heavy ion trajectories are noted: 1. 'Parabolic' trajectories, in which heavy ions injected at the polar cusp at small pitch angle rise then fall into the polar cap atmosphere, and 2. 'Hopping' trajectories, in which heavy ions injected at large pitch angles at the polar cusp mirror beteen the gravitational stopping location and magnetic mirror point as they convect at low to intermediate altitudes across the polar cap. It was also illustrated how during conditions of sunward convection in the central polar cap, a pronounced 'spray' of ions injected on the nightside may occur, in which such ions may appear in the nightside or dayside magnetosphere depending upon injection characteristics and dusk-to-dawn convection electric field magnitude; such ion dynamics may be of interest in connection with thse auroras.