Ion-Scale Characteristics of the Martian Magnetic Pile-Up Boundary Layer

Abstract

The Martian magnetic pile-up boundary (MPB) delineates the interface between the magnetosheath and the induced magnetosphere, but its global ion-scale characteristics remaining unclear. Utilizing a three-dimensional Hall magnetohydrodynamic (MHD) model, this study aims to reveal the features of the MPB layer, including magnetic field, current density, electric fields, and energy transfer between the fields and solar wind as well as planetary ions. Simulation results indicate that magnetic fields tend to pile-up, drape, bend, and slip at the MPB, leading to the emergence of associated currents ($\mathit{J}=\frac{1}{{\mu }_0}\nabla \times \mathit{B}$) from the nightside ${+Z}_{\text{MSE}}$ electric pole and its flow toward the dayside ${-Z}_{\text{MSE}}$ electric pole along the MPB. Furthermore, energy transfer analysis demonstrates that the solar wind transfers its energy to planetary ions through the motional electric field while simultaneously acquiring some energy from the Hall and ambipolar electric fields at the MPB, resulting in an asymmetrical flow of solar wind and planetary ions.