The back flow of charge-exchange (CEX) ions in the ion thruster plume affects normal operation of the satellite.The ion thruster plume model was established and a numerical simulation using particle-in-cell (PIC) method was adopted to obtain CEX ions distribution in the plume.The simulation results agree well with the flight measurement results of deep space one spacecraft.Influential factors to the distribution characteristic of CEX ions surrounding the spacecraft were analyzed

including:spacecraft potential

electron temperature

thruster operation parameter and size of spacecraft.It shows that CEX ion density surrounding the spacecraft varies from 108m-3 to 1012m-3.The CEX ion density in the measurement point varies from 0.65×1012m-3 to 1.5×1012m-3 when the spacecraft potential varies from -15V to 27V.The distribution of CEX ion density and electrical potential structure varies slightly with the electronic temperature.However

the magnitude of the electrical potential is proportional to the electronic temperature.The CEX ion density at different thruster operation points can be induced accurately according to the relationship between the CEX ion generation rate and the thruster's operation parameter.The surface of the spacecraft onto which the thruster is installed in fact shields the backflow of CEX ions.