Research on the keeper electrode's sputtering mechanism of the ion thruster

Bombardment of the keeper electrode by high-energy ions limits the lifetime of the ion thruster. To investigate its sputtering mechanism, this paper established a two-dimensional simulation model and applied the Particle-In-Cell method to simulating the generation process of the high-energy ions and their sputtering process on the keeper electrode surface. The Monte Carlo Collision method was used to address the collisions between particles. The results showed that the plasma potential downstream of the keeper electrode oscillated; therefore, ions in this area were accelerated and their energy was increased from 0.085 to 35 eV, which was enough to erode the keeper electrode's surface. double charged xenon (Xe++) ions and charge exchange xenon (CEX) ions were the two kinds of high-energy ions. The most severe position was the center of the keeper electrode surface, and its erosion rate was about 2.0 × 10-4 m/1000 h, while the average erosion rate was about 10-5 m/1000 h when the frequency and the amplitude of the plasma potential were 50 Hz and 35 eV, respectively. Plasma potential oscillation greatly affected the sputtering mechanism of the keeper electrode.