Numerical Simulations Of Spacecraft Charging In The Solar Wind

Spacecraft charging issues will affect the working status of the spacecraft andeven cause spacecraft anomalies. Spacecraft charging researches provide importantreferences for the design of the spacecraft. In this thesis, both analytical method andthe FD-PIC method are used to simulate the spacecraft surface charge and thecharacteristics of the sheath formed in the process of charging.In the effects of the light and the solar wind, there can exist three types ofsheath profiles: one kind of sheath which has a potential barrier, one kind of sheathwhich potential decreases monotonically and one kind of sheath which potentialincreases monotonically. In the numerical simulation, the surface of the spacecraftis simplified as a plane model, the speeds of electrons and photoelectrons areassumed satisfy Maxwell distribution. According to the velocity distributionfunctions, we get the densities of ions, electrons and photoelectrons. By solvingpossion equation, we get the electrical potential distribution, the electric fieldintensity distribution and charge density distribution. Then, based on the sheathmodel established by the analytical method, we analysis the effect of the driftvelocity of the solar wind on the characteristics of the sheath and the trend of thesheath with the solar wind drift direction changes. In FD-PIC method, appropriateregional and boundary conditions are selected. The concept and methodologyassociated with particle loading and injection are given. Thus, the sheath model isalso built by the FD-PIC method.In the same space environment parameters, the results obtained by theanalytical method are used to verify the correctness and feasibility of FD-PICmethod which is used to simulate spacecraft surface charge. Finally, the oscillationof potential are discussed and it can be reduced by increasing the number ofsimulation particles in the simulation region and reducing time step.