High-density nano-capillary ionic liquid electrospray thrusters with improved emitter uniformity and extended operating voltage range

Ionic liquid electrospray thrusters are promising micropropulsion devices for nanosatellites; however, their performance is often limited by low thrust density. To address this limitation, this study develops electrospray thrusters using field emitter array fabrication techniques to increase emitter density. However, previous designs suffer from non-uniform emitter geometries and propellant leakage. Herein, the fabrication process was optimized to suppress ionic liquid leakage and achieve stable ion emission. The capillary apertures were minimized by improving the geometric uniformity of the emitter array. Experimental results demonstrate that the stable operating voltage range expanded by a factor of 4.4 compared with that reported in the previous study. The thruster achieved a current density of 34 mA cm −2 , which is among the highest values reported for this class of devices. In addition, the ion beam interception rate was significantly reduced. Furthermore, a cleaning process combining acetone and oxygen plasma reactive-ion etching was developed to eliminate organic residues derived from the ionic liquid. This process was demonstrated as a proof-of-concept for single-cycle restoration of microfabricated emitter arrays in laboratory experiments, thereby mitigating the challenges associated with long production times. These results demonstrate that improved fabrication uniformity and preliminary device restoration procedures represent meaningful steps toward the development of high-performance micropropulsion systems.