Interaction of Relativistic Electrons with Finite-Length Packets of Electromagnetic Ion-Cyclotron Waves in the Earth’s Magnetosphere

We consider the interaction of relativistic electrons with finite-length packets of electromagnetic ion-cyclotron waves in the Earth’s radiation belts. On the basis of the numerical simulation by the test particle method, we study the dependence of the interaction characteristics on the length and amplitude of the wave packet both in the linear and nonlinear regimes. The fluxes of the particles precipitating to the loss cone as a result of the considered interaction are calculated. We show that both in the linear regime and under the regime of force bunching caused by the direct influence of the Lorentz force on the electron phase, the decrease in the packet length expands the interaction region to low energies outside the range of resonance values for the central packet component. Such an interaction can lead to precipitation of hundreds-keV electrons into the ionosphere. Nonlinear effects lead to saturation of the precipitation flux at the limiting level corresponding to the strong pitch-angle diffusion.