Effects of decreasing ionospheric pressure and the plasma mixing recess on the solar wind interaction with non-magnetized planets Original Research Article

The solar wind interaction with the ionosphere of non-magnetized planets is numerically simulated in the framework of 3-D magnetohydrodynamics (MHD) with two-component plasma. In cases 1 and 2, solar extreme ultraviolet (EUV) flux values is set so the peak ionospheric plasma pressure is below and above the incident solar wind dynamic pressure. While the formation of the bow shock and the magnetic barrier in the upstream region is seen in both cases, a clear formation of the ionopause is seen only in case 2. In case 1, the interplanetary magnetic field (IMF) penetrates from the magnetosheath to the dayside ionosphere so as to adjust the ionospheric total pressure. Penetrating IMF affects the vertical motion of the ionospheric plasma. However, formation process of the ionotail is little affected by the penetrating IMF. In bith cases 1 and 2, partial penetration of the IMF occurs from the magnetic barrier to the terminator ionosphere. This nonideal MHD process characterized by the penetration of flowing magnetized plasma into non-magnetized plasma plays a principal role in the mixing interaction between the solar wind and the planetary ionosphere.