Design of input parameters and operating characteristics for multi-mode ion thruster

Abstract

In view of the requirements for the application of electric propulsion system to China's asteroid deep space exploration mission, the relationship between input parameters and output characteristics of the thruster is established based on the basic plasma theory, and the input parameters such as screen grid voltage, beam current, anode current, acceleration voltage and propellent flow rate at each operating point are designed. The operating characteristics of the thruster are studied experimentally and theoretically. The test results show that under the design input parameter values, the maximum error of thrust is less than 3% and the maximum error of specific impulse is less than 4% at 23 operating points, the ion thruster can operate steadily in an input power range of 289–3106 W, thrust range of 9.7–117 mN, specific impulse range of 1220–3517 s, and efficiency range of 23.4%–67.8%. The electron backstreaming limited voltage decreases monotonically with thrust increasing and its minimum and maximum thrust value are 79.5 V and –137 V, respectively. The discharge loss decreases from 359.7 to 210 W/A as the power increases, and there is an adjusted turning at the input power 886 W, the efficiency increases with power increasing and after 1700 W the efficiency growth rate slows down and stabilizes. The optimum operating interval should be selected in practical on-orbit application. Controlling these parameters reasonably can improve thruster performance and lifetime. A 300-h wear test shows that the thruster works stably and the performance indicators meet the design requirements of ±3% uncertainty.