Resonant Interaction of Relativistic Electrons with Electromagnetic Ion–Cyclotron Waves. II. Integral Parameters of Interaction Regimes

We analyze the integral parameters of resonant interaction of relativistic electrons in the Earth’s radiation belts with electromagnetic ion–cyclotron waves. The analysis is based on numerical simulations. Wave packets of finite length with varying frequency and various amplitude profiles propagating from the equator are considered. The roles of three nonlinear interaction regimes, analyzed in the first part of our paper [1] for single particle trajectories, are compared. It is shown that interaction characteristics depend stronger on the electron energy and wave packet position for the wave packet with Gaussian amplitude profile than for the wave packet with constant amplitude. For the wave packet with Gaussian amplitude profile, the directed and diffusive transfer of particles in the phase space are comparable, while for the wave packet with constant amplitude the mean change in the equatorial pitch angle can be considerably (a factor of 3 to 5) greater than the standard deviation. The most significant decrease in the equatorial pitch angle and the largest fraction of the corresponding particles are obtained for particles with energies of about 1 MeV for the wave packet close to the equator. The fraction of particles which can be scattered into the loss cone after a single pass through the wave packet is 1.0–1.7%.