Wave-particle interaction at the plasmasphere-ring current interface

During the plasmasphere filling process following geomagnetic storms, an outward density decrease of the cold plasma at L=3-4 is typically observed. When this structure overlaps with the sharp inner edge of the ring current, wave activity is detected at linearly stable phase velocities. The excitation of these waves around the lower hybrid frequency and their effects on the heating of thermal ions is analyzed. It is found that lower hybrid drift waves are most effective at heating lower mass ions, e.g., plasmaspheric H⁺, versus He⁺, which may be heated more effectively by electromagnetic ion cyclotron waves driven unstable by the ring current loss cone