背景压强对电推进羽流场影响的数值模拟

The background pressure in vacuum chamber is an important parameter that affects the performance evaluation and plume field parameter diagnosis of electric thruster during ground tests. In this paper, a simulation analysis was made on the background pressure establishment method used in the numerical simulation of the plume field parameters of LIPS-200 ion thruster. The hybrid particle in cell (PIC) method and the direct simulation Monte Carlo (DSMC) method were used to deal with plasma motion and particle collisions in plume field. The electric propulsion plume was numerically simulated by using virtual particles and computed particles respectively, and compared with the vacuum environment. The results show that the number densities of neutral particles and charge-exchange ions are more than one order of magnitude higher than those in the vacuum environment due to the existence of background pressure. The virtual particles can greatly improve the computational efficiency, and the charge-exchange ion distribution in the plume field obtained is similar to that of the computed particle. However, the neutral particle distribution is quite different, so the influence of the wall and vacuum pump cannot be characterized by virtual particles.