The Development Of EPIC Model And Simulation Code And Their Applications In Studying Magnetic Reconnection

With the development of the technology of plasma experimental diagnosis and space satellite observation, especially the launch of the Space Environment Simulation and Research Infrastructure(SPERF, the national significant infrastructure for science and technology) and the MMS(Magnetosphere Multi-scales Mission) satellite, the electron dynamics in electron inertia scales have attracted intensive attention by scientists. However, numerical simulation, as one of the most important methods to investigate plasma physics, still needs further development focusing on electron dynamics. So far, only the Electron Magnetohydrodynamics code using fluid approximation for the electron is available concentrating on t he electron dynamics, but for the kinetics dynamics of electron, the numerical model and the corresponding simulation code still needs to be developed. Thus we perform the EPIC(Electron Particle-in-Cell) model focusing on the electron dynamics with the fast time scale and small space scale, e.g. electron inertia scale. In the EPIC model, electrons are simulated as particles using PIC(Particle-in-Cell) method and ions are described as fluid, so that it can simulate the dynamics of electrons efficiently with the consideration of ions moving in a large space scale.In the thesis the basic content of EPIC model is introduced and the corresponding EPIC model equations are demonstrated. The EPIC equations are simplified according to fast timescale approximation to obtain equations applied to the code development. Then the process procedure of EPIC numerical simulation is constructed in the framework of EPIC model. And under the guidance of the process chart, the coordinate system, Yee grid and weighting method for code is constructed. Also the Yee grid in two dimensions is designed. Electromagnetic equations are dispersed and the method converting electromagnetic field in dual grid point to grid point is introduced. The stability conditions and the boundary conditions are also discussed. Finally, the EPIC code is completed.With the EPIC code, the dynamics of the magnetic reconnection in the space is simulated and program verifying is conducted. Some preliminary research results have been achieved. At first, the basic theory of the magnetic reconnection is presented and the forming process of Hall quadrupolar field is analyzed. After that, EPIC code is used to simulate the magnetic reconnection process relating to the magnetic reconnection in the Earth’s magnetotail. Several essential physical characteristics of magnetic reconnection have been obtained, and then the simulation code has been proved. Furthermore, the code is applying to investigate the driven magnetic reconnection process, and gets some preliminary achievement. From the simulation results, it can be seen that the magnitude of driven flow has significant effect on t he Hall quadrupolar field and reconnection progress. The driven flow can obviously enhance the Hall quadrupolar field and increase the reconnection rate. Also the effect of the driven flow distribution on reconnection rate is studied. It can be obtained that the reconnection rate rises generally with the increase of the width of the driven flow. This work of the EPIC simulations lays the foundation for studying all kinds of physical progress in electron inertia scale with the EPIC code.