Xiao-Dong Wang (IRF)Date:
AniaraThe dependence of Martian ion escape rate on the solar wind conditions: results from hybrid simulations
Swedish Institute of Space Physics
We investigate the dependence of Martian atmospheric ion escape rate on the density of the upstream solar wind using a hybrid model. The model is run for 13 logarithmically distributed densities ranging from 0.2 cm^-3 to 6 cm^-3, with a fixed ion production distribution and the solar wind velocity at 400 km/s. The simulated escape rate shows a minimum at 3 cm^-3 solar wind density and increases by a factor of ~3 as the density decreases to 0.5 cm^-3. Such a negative dependence in the most probable density range is consistent with the recent observational results from Mars Express. The simulation results show that ions escaping inside the induced magnetosphere at energies lower than the solar wind energy prevail in this solar wind density range. These ions are subject to the JxB force, therefore the energy per ion increases with increasing solar wind density. The resultant escape rate, however, decreases because the total amount of energy available for escape increases slower due to the compression of the induced magnetosphere.
Created 2015-03-30 09:55:11 by Mats HolmströmLast changed 2015-03-30 11:20:32 by Mats Holmström