Influence of tail-like magnetic field on O⁺ ion distribution in the Martian magnetosphere

Based on the comparison with the Earth, using the LB magnetic field model, the distribution of O⁺ ion originating from the ionosphere in the Martian magnetosphere is theoretically studied under different conditions of the tail-like magnetic field. The results show that the tail-like magnetic field has influence on the O⁺ ion flux in the Martian magnetotail: ( i ) the O⁺ ion flux in the Martian tail will increase if the tail-like magnetic field increases; when the tail-like magnetic field increases from 5 nT to 20 nT, the O⁺ ion flux increases 3 times in the region of 2.8 R_m in the Martian tail; and ( ii ) the O⁺ ion flux decreases with increasing intrinsic moment; when the intrinsic moment increases about 5 times, the flux decreases to one fourth in the region of 2.8 R_m in the Martian tail. According to the data on the O⁺ ion flux and theoretical result in this paper, the deduced Martian intrinsic moment is about 2 × 10²¹ Gcm³. This is consistent with the most recent observation by the USA satellite MGS.