The plasma thruster developed by our research team is an Applied-Field MagnetoPlasmaDynamic (AF-MPD) thruster, a type of high-power electric propulsion, and is a future electric thruster that can be used for deep space exploration and space tugs. Although there is no flight heritage yet, it is a thruster that is being actively studied in Germany, Japan, and China because it has a simple geometry and is easy to achieve high power operation. Our research team has developed both permanent magnet- and electromagnet-based AF-MPD thrusters and has been successfully operating them up to 15 kW.
To evaluate the performance of the thruster after the development of AF-MPD thruster, a thrust stand was constructed as shown in the below figure. The calibration of the thrust stand was carried out using weights and pulley and it was confirmed that our thrust stand linearly produces a signal of 4.8 mV per 1 mN. Then, the thrust and specific impulse were measured in Ar plasmas and the results are shown in the below figure. Both the thrust and the specific impulse were measured to be linearly increased as increasing the applied power from 2 to 15 kW. It was also found that a thrust of 430 mN and a specific impulse of 2900 s were generated at approximately 15 kW.
한편, Space X의 Starlink 이후 국제적으로 저궤도 군집위성에 대한 관심이 높아지고 있다. 우리나라도 감시/정찰 목적으로 40 대의 초소형 위성을 2030년까지 발사할 계획이다. 우리 연구실에서는 이러한 초소형 위성에 쓰일 수 있는 초저전력 이온추력기 기술을 한국핵융합에너지연구원, 한국항공대학교와 함께 개발하고 있다. 현재 랩 모델을 성공적으로 개발하였고 1.2 mN의 추력과 1200 s의 비추력이 발생하는 것을 확인하였다. 향후 고체연료 기술을 추가하여 초경량, 초소형 이온추력기 기술을 확보할 계획이다.