Performance experiments of the dual-stage 4-grid ion thruster were conducted. Experimental results showed that the specific impulse reached 7100 s and the beam divergence angle reached 6.3°when the screen and extraction potentials were 4.5 and 2.5 kV, respectively. The test results of beam extraction characteristics showed that the extraction capacity of ions was determined by extraction potential and was independent of screen grid and acceleration stage potentials. The extraction capacity of ions was analyzed with plasma sheath theory, and conclusions were in accordance with the experimental results. This study presents the decoupling mechanism of ion extraction and acceleration processes of the dual-stage ion 4-grid optical system by experiment and simulation.

This study aimed at discussing the laws of the design parameters of a radio frequency (RF) ion thruster that influence the thruster performance, guide the performance optimization-oriented design of the thruster, and realize the high-accuracy continuous adjustment of the thrust performance. The key influencing parameters of the thrust performance were analyzed by the numerical simulation method. The influencing laws of RF parameters on key plasma parameters, as well as the thermal characteristics of the thruster under the rated parameters, were explored. Moreover, a LRIT-30 RF ion thruster was developed and subjected to the performance adjustment test. The research results demonstrated that the simulation model can describe the plasma parameter distribution of the discharge chamber and the thermal distribution of key components. The 3 cm RF ion thruster performs well under 2 MHz operational frequency. The RF power and gas flow rate are the key influencing factors of beam extraction and are appropriate for the accurate adjustment of parameters. The wide-range adjustment of thrust (0.5–2.3 mN) and specific impulse (869–2564 s) can be realized when the screen-grid voltage, decelerating screen voltage, RF power, and gas flow rate are 1500 V, −200 V, 40–65 W, and 0.4–0.8 SCCM, respectively. The performance indices of the proposed RF ion thruster are close to the international advanced level.

Abstract-This paper aims to study the plasma discharge process of a 5 kW hall thruster developed by Lanzhou Institute of Physics and to provide the knowledge for implementing an improved thruster design. A 2D Particle-In-Cell (PIC) model is built, in which the electron-electron and electron-ion Coulomb collisions are included, in addition to the elastic, excitation, and ionization collisions between electrons and neutral atoms, and the elastic and charge-exchange collisions between ions and neutral atoms. Different Bohm diffusion coefficients are applied in different regions to simulate the Bohm diffusion. The deviation between the simulated and experimental results of the thruster performance is within 15%, validating the accuracy of the model indirectly. The discharge process including the transient and steady-state oscillations is well reproduced. The character of the plasma during different phase of the discharge process including the ion density and ionization rate is simulated and analyzed. Finally, the probable factor causing the anode erosion is determined.

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In this study, the numerical simulations are used to simulate the discharge process of a 10-cm dual-stage 4-grid (DS4G) radiofrequency (RF) ion thruster, and the effects of RF coil turns, and electrical parameters on the key plasma parameters inside the discharge chamber are investigated. Thus, the optimal design parameters of the thruster are obtained. The RF plasma source has high inductive coupling discharge efficiency when the number of coil turns is six and the operational frequency is 2 MHz. The simulation results show that increasing the number of coil turns can effectively increase the plasma density inside the discharge chamber, and thus improve the efficiency of the inductive coupling discharge, and the operational frequency affects the characteristics of the inductively coupled discharge by influencing the depth of the plasma skinning layer. An experimental thruster demonstrated the 10-cm DS4G RF ion thruster can achieve super high specific impulse. The correctness of the simulation model is verified by the experiment results of the thruster, which will be useful for the optimal design of radio ion thruster or ion sources.