Features of ion trajectories in the polar magnetosphere

In the present polar magnetosphere model, which includes the effects of convection electric fields and gravitation, the trajectories of mainly low energy ionospheric ions injected near the polar cusp into the polar magnetosphere display the ion mass and energy differentiation seen in recent satellite observations of low energy ionospheric ions. Two interesting trajectory classes are noted for low energy heavy ions: parabolic trajectories, in which ions injected into the polar cusp at small pitch angles rise, and then fall, into the polar cap atmosphere, and 'hopping' trajectories, in which heavy ions injected at large pitch angles at the polar cusp will mirror as they convect at low to medium altitudes across the polar cap.