Effect of Hot He+ Ions on the Electron Pitch Angle Scattering Driven by H+, He+, and O+ Band EMIC Waves

Abstract

In this paper, we find that hot He+ ions significantly alter the kinetic dispersion relation of electromagnetic ion cyclotron (EMIC) waves and thus strongly affect the wave-driven electron pitch angle scattering rates. Increasing hot He+ ion parallel temperature, temperature anisotropy, or abundance raises the pitch angle scattering rates of MeV electrons driven by the H+ band EMIC waves. During the electron resonance with the He+ and O+ band EMIC waves, the electron pitch angle scattering rates are more sensitive to the variation of temperature anisotropy and abundance of hot He+ ions than their parallel temperature. The increase of hot He+ ion abundance (temperature anisotropy or abundance) generates a reduction of the energy range of electrons interacting with the He+ (O+) band EMIC waves. Therefore, the effect of hot He+ ions on the EMIC wave-driven electron pitch angle scattering should be involved in the radiation belt modeling.