Wave-Particle Interactions and Radiation Belt Modeling in the Terrestrial and Planetary Magnetospheres

Abstract:

This study considers effect of resonant wave-particle interactions with chorus waves and determine whether chorus waves can produce net acceleration or net loss of radiation belt electrons of the outer planets. We first discuss the effects of the local acceleration and loss in the Earth Van Allen radiation belts and show examples of modeling and comparison with observations. We then present 2D simulations of pitch angle energy, and mixed diffusion simulations of the Saturnian and Jovian radiation belts. Two-dimensional diffusive simulations of local acceleration and loss to the atmosphere using the VERB code confirm previous suggestions that the acceleration of electrons may be very efficient in the outer radiation belt of Jupiter. However, sensitivity simulations also show that the result of the competition between acceleration and loss in the Jupiter’s magnetosphere strongly depends on the currently not well-known latitudinal distribution of chorus waves and energy spectra provided by other processes such as radial diffusion and interchange instability. The ratio of plasma frequency to gyrofrequency is a key parameter that determines the efficiency of the pitch angle and energy resonant scattering. While this ratio is usually very high and does not support the local acceleration in the Saturnian radiation belts, at high latitudes the ratio may significantly drop and result in the efficient acceleration of electrons. We finally discuss the acceleration by Z-mode waves that can contribute to the overall acceleration of electrons in the planetary environments.