Kinetic Alfvén waves in the overlap region between the plasmasphere and ring current

Dispersion of Alfvén waves with kinetic effects taken into account is analyzed within the framework of a plasmasphere model featuring a realistic parameter distribution and inclusion of hot ring-current protons. It is demonstrated that the dissipative transition layer—the region where the type of Alfvén wave dispersion changes—encompasses nearly the entire plasmasphere region adjacent to the plasmapause. In this region, Alfvén waves exhibit warm dispersion. The presence of hot ring-current protons results in a width reduction of the transition layer and shifts it toward the inner boundary of the ring current. The modification of the transition layer by hot protons, in turn, strongly affects the dissipation of kinetic Alfvén waves into cold electrons near the plasmapause.