火星空间大尺度电流体系分布特征

在MHD模型基础上, 对火星空间环境的电流分布进行了模拟. 结果表明, 火星空间存在着弓激波电流、磁堆积区电流、电离层电流和磁尾电流. 弓激波电流在激波曲面上均由北向南自成体系, 电流密度在弓激波顶区域较大. 在向阳面磁堆积区边界电流与电离层电流彼此耦合形成完整的回路, 在背阳面磁堆积区边界电流与磁尾中心电流片耦合形成完整的回路. 

Global Distribution of Currents in Martian Space

Based on the MHD model, distribution of the currents in Martian space is calculated. The results show that there are 4 categories of currents, i.e., the bow-shock current, magnetic pileup boundary current, the ionosphere current and the magnetotail current in Martian space. Currents flow on the surface of the bow-shock independently, which direction are perpendicular to the interplanetary magnetic field direction, with the peak current density located around the subsolar point. At dayside, the magnetic pileup boundary current closes through the ionosphere; while at nightside, magnetic pileup boundary current couples with central current sheet in the magnetotail to form a complete circuit. Magnetotail central currents near Mars within 1.2R_m affected greatly by the ionosphere, would be separated for two or more current slices coupling together. The strength of ionosphere current, flowing from south to north, is the biggest in all, more than 100nA·m-2 in average; and the strength at dayside is bigger compared to that of the nightside.