Loss of energetic electrons in the vicinity of Io

Io plays a dual role in the Jovian magnetosphere, that is, its active volcanism provides a main plasma source of the magnetosphere, and it loses energetic particles within radiation belts as well which has been observed by spacecraft (Galileo and Juno). On 12 February 2019, the Juno spacecraft crossed the particle drift shells (L shells) of the moon Io and found a wide and a narrow decrease in the energetic electrons which are thought to be dominantly caused by wave-particle interactions. Via including moon absorption and wave-scattering induced by hiss waves, we simulate the evolution of electron fluxes by the radial diffusion equation. Our results show that the moon absorption dominates the loss of energetic electrons, and hiss waves play a secondary role in decreasing the fluxes of energetic electrons in the vicinity of Io but can widen the radial distance of the decrease of electron fluxes. Furthermore, simulation results indicate that the pitch angle distributions of energetic electrons will transfer to 90°-peak distributions due to moon absorption and hiss scattering. Our study helps to deepen the comprehensive understanding of the dynamic evolution of energetic electrons in the vicinity of Io.