Multi-fluid MHD Study of the Solar Wind Induced Plasma Escape from the Martian Atmosphere

In this study, the multi-fluid MHD model (Najib et al., 2011) is further improved to include an electron pressure equation to self-consistently calculate the electron temperature. The electron pressure equation included in the improved model can accurately calculate the electron temperature and the electron pressure force. The electron temperature is also needed to calculate rates of some electron temperature dependent chemical reactions such as dissociative recombination and electron impact ionization. So the improvement of the model leads to a more accurate evaluation of the ion density in the ionosphere and a more accurate description of the interaction process. Model results of a typical case with electron pressure equation included are compared in detail to an identical case without the electron pressure equation to identify the effect of the improved physics. The two cases will be examined to identify changes in the global interaction patterns. Electron temperature will also be compared for the two cases to identify regions where temperatures differs the most. The ion density profiles at different locations will be compared to identify the changes of plasma density due to changes of recombination rates and impact ionization rates caused by different electron temperatures. The calculated electron temperature profile will also be compared to the only available pre-MAVEN electron observations from the Viking Retarding Potential Analyzer (RPA) (Hansen et al., 1977). Based on model results, two-dimensional maps of the ion densities and fluxes are to be generated in the tail region at various distances to locate the intense region for plasma bulk escape. We will also plan to fly through the 3D MHD model results using planned MAVEN orbits to predict when and where the spacecraft will pass different plasma boundaries (such as the bow shock, MPB, and ionopause), and the typical range of the plasma parameters in different regions.