Dynamics of the Ions at Ganymede's Magnetopause

Abstract:

We study the dynamics of the oxygen and hydrogen ions at Ganymede’s magnetopause when Ganymede is inside the Jovian magnetosheet using a combination of a hybrid model of plasma and a test-particle simulation. We investigate the contribution of the different electric field terms, including the convective, Hall, ambipolar, and Ohmic and we find that the Hall term is the most dominant one at the magnetopause and in the magnetotail. Inside the magnetosphere, in a region of low density on the upstream side, the Ohmic term dominates. In the almost undisturbed plasma outside the magnetosphere, the convective term dominates. The ambipolar term, the term related to electron pressure gradients, has no large region of dominance. We also investigate the energization of ions interacting with the magnetopause by running a test particle model for oxygen and hydrogen ions. We found that the energy of particles interacting with the magnetopause will on average increase by a factor of 10 for oxygen ions and by a factor of 50 for hydrogen ions. The energy of these ions will be mostly between $10^3$ and $10^5$ eV for both species after interacting with the magnetopause.