Mode transitions in Hall effect thrusters by Varying duty ratio under pulsating operation

During the operation of a Hall effect thruster, small changes in discharge voltage, mass flow, or magnetic field cause significant changes in the discharge mode of the thruster. Keeping other working conditions unchanged, the discharge mode of the Hall effect thruster can be triggered by changing the duty ratio. The experimental results show that at different frequencies, a small change in the duty ratio caused a significant increase in the discharge current and discharge oscillation amplitude. When the duty ratio changed from 70 % to 68 % at 90 kHz, the discharge mode changed from high- to low-oscillation mode. The discharge current oscillation decreased from 1.03 to 0.66, and the anode efficiency increased from 24.5 % to 25.8 %. When the duty ratio was changed from 64 % to 58 % at a pulse frequency of 70 kHz, the discharge current oscillation decreased from 1.26 to 0.85, and the anode efficiency increased from 23.5 % to 24.8 %. In the low-oscillation mode, the discharge current and anode voltage of the thruster were at the same frequency, and the discharge oscillation of the thruster was significantly reduced. Furthermore, the Faraday probe measurement results showed that the ion current density distribution of the thruster was more focused. The match between the supply of the working medium and the ionization rate improved the degree of ionization, leading to an improvement in thrust performance. Maintaining the Hall effect thruster in low-oscillation mode is of great significance for improving the reliability of the thruster.