The Impact and Mechanism of Magnetic Fields on Plasma Dynamics in the Martian Space Environment

The absence of a global magnetic field at Mars results in a direct interaction between the solar wind and the ionosphere, leading to ion escape from its atmosphere to space. However, the existence and asymmetric distribution of crustal fields introduce significant complexity into the plasma dynamics within the Martian environment, resulting from a disordered magnetic field topology characterized by its orientation parallel, directed towards, and away from the Martian surface. Based on three-dimensional multifluid magnetohydrodynamic simulations, we investigated the impact of the magnetic inclination angle on the Martian ionospheric plasma dynamics under the typical solar wind conditions. Numerical results showed that ions can be effectively diffuse upwards along vertical magnetic fields driven by the electron pressure gradient and the motional electric force, leading to a strong outward flux escaped through plume and the magnetotail eventually. In addition, due to the Hall electric force, there is a tendency for ion flow to be deflected in the horizontal plane. These results provide valuable insights into the influence of magnetic fields on ion motion in the Martian space environment.