Theoretical distribution of O+ ions in the Martian magnetosphere

Considering the magnetic field measurements obtained recently by Mars Global Surveyor and the data on ions in the Martian environment, a model is developed to study the flux distribution of ions originating from the Martian ionosphere along magnetic field lines with different assumed intrinsic moments. Furthermore, the Martian intrinsic moment is deduced. The results show that the intrinsic moment has an influence on the flux distribution of O+ ions, i.e., the stronger the intrinsic moment, the more quickly the flux of O+ ion will decrease with increasing distance from Mars and the lower of the flux of O+ ions will be in the tail. By comparison of the theoretical result in this paper with the observations, the deduced Martian intrinsic moment is about 2 x 10(21) G(.)cm(3). (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.