Predicting Field-Aligned Currents and Precipitating Particle Intensity Profiles at Jupiter

Abstract:

While in orbit around Jupiter, the Juno spacecraft has observed “inverted-V” potentials on the order of megavolts aligned with magnetic field lines connected to the high-latitude regions of the ionosphere. These field lines extend to Jupiter’s middle magnetosphere at radii of 20R_J – 50 R_J. Such potential structures can accelerate charged particles, with Juno’s Jupiter Energetic-particle Detector Instrument (JEDI) observing planetward acceleration of electrons and ions towards energies of MeV.

The coupling between the magnetosphere and ionosphere is a complex process with many facets, including the generation of electric fields, development of field-aligned currents, precipitation and outflow of particles, all of which require consideration to fully understand the dynamics of system. To that end, we employ a 1-D spatial, 2-D velocity space Vlasov treatment of these high-latitude field lines to examine the behaviour of plasma along them. By meshing the simulation domain with a non-uniform grid and utilising the benefits of code parallelisation, a fine mesh can be applied to the ionospheric end of the field line, allowing small scale spatial and temporal features to be resolved without impeding on the computational runtime. This allows the determination of the potential structure and plasma density profiles along the field line, as well as the precipitating particle intensity. We present results based on select Juno measurements and compare the output of the model to in-situ data.