3-DIMENSIONAL MHD SIMULATION OF THE SOLAR-WIND INTERACTION WITH THE IONOSPHERE OF VENUS - RESULTS OF 2-COMPONENT REACTING PLASMA SIMULATION

The large-scale solar wind interaction with the Venusian ionosphere is numerically simulated in the framework of two-component, three-dimens ional magnetohydrodynamics (MHD). The finite volume total variation di minishing scheme is used to solve this problem. The impinging solar wi nd is represented by H+ ions, and the ionosphere is assumed to consist of O+ ions produced by photoionization of atomic oxygen in the Venusi an upper atmosphere and by charge exchange of CO2+ ions. The O+ ions a re lost by charge exchange with carbon dioxide molecules. The numerica l simulations are performed for interplanetary magnetic field (IMF) pe rpendicular to the solar wind flow and for the solar wind parameters w hich correspond to maximum solar activity. Results of the calculation give the formation of the bow shock, the magnetic barrier, and the ion opause in the dayside region as a self-consistent state of the interac tion processes. The dynamical behavior of the dayside ionosphere under the influence of the impinging solar wind and the IMF slipping over t he pole results in the formation of wing-like bulges of the ionosphere and an accompanying poleward flow in the topside ionosphere. The mode l also reproduces several features of the nightside ionosphere that ar e predicted by earlier theories and observations, including complex st ructures such as a flattened ionotail, tail rays, and ionospheric hole s, as a continuation of the wing-like bulge. It is also shown that slo w plasma flow in the ionotail and nonideal MHD process play important roles in the formation of the induced magnetotail of the planet.