Taylor Cone and Ionization Experiment for Development of mN FEEP Thruster With Annular Slit Type Emitter

Field emission electric propulsion (FEEP) is deemed the most suitable ion thruster for nano-satellite's deep space exploration and precision maneuver due to its low thrust and high specific thrust. Research on annular slit has never been carried out except for some conceptual patents, which can offer high space efficiency, and zero ion beam lost at the end of the slit. Therefore, it is important to set a design target value through system analysis for the present research. Here, voltage, slit length of emitter, and current per slit length for maximum thrust and minimum power are calculated via system analysis as a basic level of development. To understand the basic principle for the actual development, Taylor cone experiment utilizing various types of emitters, ionic liquid ion source (ILIS) was carried out. In addition, ionization experiment using liquid metal ion source (LMIS) was conducted. The results elucidate that multi-cones can be formed at annular slit emitter from ILIS, which is experimentally accessible. The work in progress is extended to LMIS, where ionization of liquid indium occurred at annular slit emitter, which confirmed the possibility of a working annular slit emitter.