Energetic Plasma Injections in Jovian Inner Magnetosphere: A Simulation Study

Abstract

AbstractOutward transport of cold iogenic plasma and energetic charged particle injections are two essential aspects of mass, energy and magnetic flux circulation in the Jovian magnetosphere. However, it is unclear how these two processes interplay and how they evolve globally in the Jovian inner magnetosphere. We use the improved Rice Convection Model‐Jupiter to simulate the concurrent energetic injection and cold plasma convection in Jupiter's inner magnetosphere. The effects of plasma density, injection site location and energy of energetic particles on the plasma injection are parametrically investigated through a series of runs. The model successfully reproduces the energy‐time dispersion signature of energetic particles that may be observed by a spacecraft during an injection event. Simulation results show that the energetic injection is mainly driven by the electric field associated with the cold plasma outflow. Energetic particles are transported inward in the form of elongated fingers which appear interlaced with those of cold iogenic plasma. The injected particles are strongly modulated by the gradient/curvature drift, especially in inner regions close to the planet, and show a significant dispersion feature during the evolution. The radial velocity of the injection decreases from over 100 km/s at L = 20 RJ to less than 10 km/s at L = 10 RJ, while the related field‐aligned currents tend to increase during the inward injection. The energetic plasma density and the injection site location are found to have little effect on the plasma injection, provided that their effect on cold plasma convection is negligible.