Investigation Ion Beam Extraction for Increase Thrust, Efficiency, and Lifetime of RF-ICP Ion Thruster

Using COMSOL Multiphysics software, the influence of the applied power, injected gas pressure, and coil placement configuration are studied on a radio frequency (RF) inductively coupled plasma (ICP) source-based ion thruster system. In order to reach a long-life ion thruster with high efficiency, the RF-ICP source and extractor system of the thruster is simulated in three dimensions under different conditions. The simulation results show that displacement of the ICP coil can push the generated plasma density pick to the vicinity of the extractor electrode. The variations of the RF power and the injected gas pressure are investigated on the current density of the extracted beam. Considering space charge effects, beam optical parameters, and gas diffusion effects, an optimum injected gas pressure is obtained in the order of 2.5 Pa, at a fixed RF power of 300 W. The efficiency of the three types of extractor electrodes (A, B, and C types) is compared with each other. This study, under the optimum pressure and the optimum RF power of the A-type extractor, is performed for all three types. The comparison results indicate that the cone-type electrode can extract a high-current ion beam with a proper divergence angle, perveance, and transparency.