Study on Effect of Structure and Propellant on Beam of ECR Ion Source

Abstract

To increase the ion current from the ion source is an important way to improve the performance of the electron cyclotron resonance ion thruster(ECRIT). The ion migration distance, magnetic topology and propellant have a close influence on the extracting ion beam. This influence is studied through both magnetic circuit structure calculation and experiments, by using an ion source with different gate mounting positions and magnet lengths. Experimental results show that the distribution of the ECR region will be discontinuous when the length of the magnet is too short. This will greatly reduce the performance of the ion source. To increase the length of the magnet is beneficial to the beam emission at high gas flow rate, but it reduces the beam emission at low gas flow rate. The effect of the ion migration distance on the ion beam is related to the plasma density in the ion source. When the gas flow rate is low, a longer gate mounting ring is beneficial to increase the ion current. When the gas flow rate is high, the different magnetic topology will cause the gate mounting ring which influences on the ion current. At low gas flow conditions, xenon gas can significantly improve the discharge stability of the ion source and increase the ion current. However, at high gas flow rate, the concentration effect of the neutral particles is too strong that affects the energy accumulation process of the free electrons. This would cause the decrease in the ion current.