Effects of propellant on Arcjet Thruster operations

To understand discharge characteristics of gases used as Arcjet Thruster propellants and effects of propellant properties on starting characteristics and operating performance of low power Arcjet Thrusters, comprehensive experimental investigation was carried out on the thrusters with various gases as the propellants. Valid experimental facilities, including vacuum facilities, propellant feed facilities, power processing unit, small thrust measurement device and experimental data collection system, were developed, structure design and material selection of the laboratory type thrusters were performed, and multi-start experiments of the thrusters using argon, nitrogen and ammonia as the propellants were achieved successfully. Abundant experimental phenomena were observed and plentiful experimental characteristic profiles were obtained. The present experimental findings show that propellant properties have significant effects on starting characteristics and operating performance of Arcjets, argon thrusters start more lightly and have the different discharge voltage vs. mass flow rate profiles, compared with nitrogen and ammonia ones, ammonia thrusters are more favorable for space missions with higher specific impulse and better overall performance, compared with argon and nitrogen ones, and Arcjet structure design should be performed on the basis that the propellant is given.