Study on the O⁺ ion distribution and escape in Martian atmosphere

In this paper, we have considered the view that the Martian magnetic moment has been gradually decreasing from the past to the present, and have calculated the O⁺ ion flux distribution along magnetic field lines and the escaping ion flux in the Martian tail with different assumed Martian magnetic moments. The results show that the O⁺ ions flux along magnetic field lines decreases with increasing distance to Mars; that the ion flux along the field line decreases more rapidly if the magnetic moment is larger; and that the larger the magnetic moment, the smaller the ion flux in the Martian tail becomes. The escaping ion flux depends on the Z-coordinate in the Martian tail. With decreasing magnetic moment, the escaping ion flux in the Martian tail is increasing. The results are significant for studying the ion loss from Mars.