Simulations of Electromagnetic Ion Cyclotron Waves and Their Effect on Ring Current Protons and Radiation Belt Electrons

Using a two-dimensional hybrid code (particle ions and inertialess fluid electrons) in dipole geometry, we investigate the evolution of electromagnetic ion cyclotron waves and their effect on ring current protons and radiation belt electrons. Ion populations simulated include anisotropic ring current protons with perpendicular temperature greater than parallel temperature, and cold protons, helium ions, and oxygen ions. The waves are excited in the vicinity of the magnetic equator, and the dominant wave mode is the He+ wave band that asymptotes to the He+ gyrofrequency at large parallel component of the wave vector. The evolution of the ring current proton distribution can be followed during the entire simulation including precipitation loss to the ionosphere. Relativistic electrons are inserted into the simulation at various times to see how these particles are affected by the waves. Our calculations suggest that the pitch angle scattering and precipitation loss of relativistic electrons due to these waves is stronger than was previously thought.