Volume 5: Innovative Solutions for Energy Transitions: Part IV

Vaporizing Liquid Microthruster Testing Under Pulsed Mode Operation R Ranjan, F Riaz, P S Lee, S K Chou

Abstract

Microthrusters are special category of propulsion device used to propel micro sized satellites. It is designed as per the mission requirements. There are various kinds of propulsion requirements such as continuous mode operation for orbit transfer (from one planet to another), orbit shift or adjustment for asteroid mining, pulsed mode operation for attitude control of satellites, and gravitation or solar drag compensation in orbit. Continuous mode operation is a high propellant consuming operation and designed cautiously to reach the destination with onboard available propellant. While pulsed mode operation is widely used for LEO (Low earth orbit) applications, where gravitation drag, atmospheric drag and solar drags are dominating. This paper focuses on the pulsed mode operation of vaporization liquid microthruster in vacuum operating condition. The pulsed mode operation involves timely thrust generation for the fine tuning of the positioning of the microsatellites. The operational timing in this mode of operation ranges from milliseconds to a few seconds at maximum. The operating time is decided based on the adjustment requirement for the positioning of the microsatellites. Vaporizing liquid microthrusters use green propellant to produce thrust. Tests are conducted under vacuum condition to simulate the actual space conditions and corresponding results are plotted. Results has shown a maximum thrust value of 290 μN at 1 sec of valve operating time, 335 μN at 2 seconds, 413 μN at 3 seconds, 524 μN at 4 seconds and 590 μN at 5 seconds of valve operating time for 200°C of a constant VLM temperature respectively. The effect of the dibble volume has also been discussed for the vaporization liquid microthruster using di-ionized water as liquid propellant.

Keywords Vaporizing Liquid Microthruster(VLM), Green propellant, Vacuum testing, Pulsed-mode operation, 3D printed microthruster.