多模式离子推力器输入参数设计及工作特性研究

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

针对我国小行星探测任务对电推进系统离子推力器设计要求,基于等离子体基本理论建立了多模式离子推力器输入参数与输出特性关系,完成各工作点下屏栅电压、束电流、阳极电流、加速电压,流率等输入参数设计,采用试验研究和理论分析的方法研究了推力器工作特性.试验结果表明:在设计输入参数下,23个工作点推力最大误差小于3%,比冲最大误差小于4%,在功率为289—3106 W下,推力为9.7—117.6 mN,比冲为1220—3517 s,效率为23.4%—67.8%,电子返流极限电压随着推力增加单调减小,最小、最大推力下分别为-79.5 V和-137 V,放电损耗随着功率增大从359.7 W/A下降到210 W/A,并在886 W时存在明显拐点,效率随功率增大而上升,在1700 W后增速变缓并趋于稳定,在轨应用可综合推力器性能、任务剖面要求、寿命,合理设计输入参数区间,制定控制策略.

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 power886 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.