[P-PS05] Mercury Science and Exploration

[PPS05-P03] Hybrid particle simulation for ions dynamics in Mercury's inner Magnetosphere

*Toramaru Takamura¹, Hideyuki Usui¹, Yohei Miyake¹, Masaharu Matsumoto² (1.Graduate School of System Informatics, Kobe University, 2.Information Technology Center, Fukushima University)

Keywords:Mercury, Magnetosphere, ion dynamics, Hybrid particle simulation

Mercury has terrestrial-like magnetosphere by interaction with solar wind plasma. However, it takes on a different appearance like the roughly 1/20 times smaller size of magnetosphere than Earth's one because of the differences in the distance from the Sun and the weaker magnetic dipole moment, according to the previous satellite observations.
In preparation for the Mercury obsevation by the BepiColombo mission, which will start in December 2025, we began to study Mercury's magnetosphere by performing three-dimensional hybrid particle simulations. This study aims to clarify the structure of Mercury's magnetosphere, the entry process of the solar wind ions into the magnetosphere, and the ion dynamics in the magnetosphere by considering the ion kinetic effects. We particularly examined the ion dynamics near the Mercury's surface, including the drift and bouncing motions in the Mercury's magnetic fields, by analyzing particle trajectories, current structure, and the interactions between ions and the fields. We will show some of the results.
In Earth's magnetosphere, the drift motion of ions is well known as a significant source of the ring current. However, their existence and structural differences in Mercury's magnetosphere are still under debate. This study will also discuss the possibility of the ring current formation and its process in Mercury's magnetosphere.