Modeling the Process of Deposition of Erosion Products on the Walls of the Gas-Discharge Chamber of an Ion Thruster

Abstract

The problem of contamination of the inner surface of the gas-discharge chamber of a high-frequency ion thruster with sputtered material of the accelerating electrode is considered. A physical and mathematical model of electrode surface sputtering by secondary ions is formulated using the sputtering indicatrix. The motion of sputtered atoms through the flow of primary beam particles is considered, and the conditions for the penetration of sputtered material into the plasma of the gas-discharge chamber are determined. The motion of impurity atoms through the gas-discharge plasma is considered taking into account the possibility of impurity ionization. It is also assumed that all impurity atoms reaching the chamber surface are condensed. Numerical modeling of surface contamination for a spherical gas-discharge chamber using carbon and titanium as the material of the accelerating electrode of the ion-optical system is performed, regardless to the chamber material. The angular distribution of particles penetrating the chamber is obtained, and the maximum velocity and localization of particle deposition on the surface of the gas-discharge chamber are estimated. The results are in satisfactory agreement with published experimental data.