NUMERICAL SIMULATION OF THE EFFECT OF VACUUM FACILITY BACKGROUND PRESSURE ON ION THRUSTER GRID SYSTEM WORK PERFORMANCE

The background pressure is one of the important factors which affect ion thruster's work performance in ground test.This paper study the influence of background pressure on grid system performance by PIC and MCC.It compares grid system working performance of 20-cm ion thruster under different backpressure,including the particle spatial distribution,potential distribution of grid system and accelerator current,as well as the number of the position of CEX ions colliding to the accelerating grid.The results accord with test result and the effect of background pressure on sputtering corrosion of accelerating grid downstream surface greater than its corrosive effects on the pore wall for the corresponding parameter of 20 cm thruster.considering the cost of test,the ground test vacuum chamber background pressure can be set to the 5×10^-4 Pa