MHD-EPIC: Extended Magnetohydrodynamics with Embedded Particle-in-Cell Simulation of Ganymede's Magnetosphere.

Tuesday, 16 December 2014: 2:10 PM
Gabor Toth1, Lars K S Daldorff1, Xianzhe Jia2, Tamas I Gombosi3 and Giovanni Lapenta4, (1)Univ Michigan, Ann Arbor, MI, United States, (2)University of Michigan, Ann Arbor, MI, United States, (3)Univ of Michigan, Ann Arbor, MI, United States, (4)Katholieke Universiteit Leuven, Leuven, Belgium
We have recently developed a new modeling capability to embed the
implicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-US
magnetohydrodynamic model. The PIC domain can cover the regions where
kinetic effects are most important, such as reconnection sites. The
BATS-R-US code, on the other hand, can efficiently handle the rest of
the computational domain where the MHD or Hall MHD description is
sufficient. As one of the very first applications of the MHD-EPIC
algorithm (Daldorff et al. 2014, JCP, 268, 236) we simulate the
interaction between Jupiter's magnetospheric plasma with Ganymede's
magnetosphere, where the separation of kinetic and global scales
appears less severe than for the Earth's magnetosphere. Because the
external Jovian magnetic field remains in an anti-parallel orientation
with respect to Ganymede's intrinsic magnetic field, magnetic
reconnection is believed to be the major process that couples the two
magnetospheres. As the PIC model is able to describe self-consistently
the electron behavior, our coupled MHD-EPIC model is well suited for
investigating the nature of magnetic reconnection in this
reconnection-driven mini-magnetosphere. We will compare the MHD-EPIC
simulations with pure Hall MHD simulations and compare both model
results with Galileo plasma and magnetic field measurements to assess the
relative importance of ion and electron kinetics in controlling the
configuration and dynamics of Ganymede's magnetosphere.