A New Proxy for Identifying Non-Adiabatic Charged Particle Dynamics in Jupiter’s Radiation Belt

Jupiter hosts the most intense and hazardous radiation belts in the solar system, populated by ultra-relativistic protons (~100 GeV), electrons (~100 MeV), and heavy ions such as O, O, S, S, and S (~100 MeV) [1].Depending on their energy, and the local magnetic field strength, these charged particles may either escape or remain confined within Jupiter's magnetosphere.The trapped particles undergo gyro-motion, bounce motion, and drift motion due to the influence of the magnetic field.However, at higher energies, these particles can exhibit non-adiabatic behavior, deviating from classical adiabatic motion.Many theoretical and computational models employ the gyro-center approximation to study charged particle dynamics in planetary magnetospheres [2].However, under non-adiabatic conditions, the validity of such approximations becomes uncertain.In this study, we perform three-dimensional relativistic test particle simulations to analyze the motion of charged particles in Jupiter's inner radiation belt.We introduce a new parameter, = , as a criterion to distinguish adiabatic and non-adiabatic particle behavior.Our results indicate that when r L exceeds 1000 km, the charged particles exhibit non-adiabatic motion.This newly proposed proxy provides a useful diagnostic for identifying adiabatic and non-adiabatic regimes of trapped energetic particles, offering deeper insights into the complex dynamics of Jupiter's radiation belts.