MHD modelling of processes in near-Earth space plasma

P. A. Sedykh - E. A. Ponomarev

ISTP, Siberian Branch of RAS, 126a Lermontov str., POB 291, Irkutsk 664033, Russia

Abstract
Direct observations of plasma distribution in the magnetosphere face with great problems because the pressure must be known everywhere in the plasma sheet at high resolution, which  in situ satellites has been unable to provide. It is known that a map of global field-aligned currents can be constructed with hourly resolution using magnetometer data from the Iridium System consisting of 66 satellites in circular polar orbits. Modelling of the distribution of the plasma pressure (at 3-12 R_E) is very important although the data from the multisatellite magnetospheric missions for these purposes would be a very expensive project. Therefore, there is a necessity to model the processes of the near-Earth space. Selecting and applying the correct initial system of equations are also very important. A combined action of plasma convection and pitch-angle diffusion of electrons and protons leads to the formation of plasma pressure distribution in the magnetosphere. Specifying the initial pressure at the boundary, it is possible to find the resultant pressure at any point on the flux line. In such a way, the field of plasma pressures in the magnetosphere is calculated. In this study, we derive a more precise expression for the plasma pressure distribution calculation. The expression takes into account particles with energy up to 300 keV. Tables 1, Figs 11, Refs 12.