Experimental Investigation On Arcjet Using Catalytic Decomposition Products Of Hydrazine As Propellant

Electric propulsion, which has an excellent performance, is taking the place of traditional chemical propulsion at present. Arcjet, one type of electric propulsion, is high at specific impulse and ratio of thrust, and good in capability of propellant. Because of the favorable compatibility of hydrazine arcjets and monopropellant chemical thrust systems, it would be significant to improve performance of the conventional monopropellant thrust system by arc heating. Hydrazine arcjet has been studied deeply in the world, however the research of arcjets in our country is little and the gap is still huge. So it makes sense to carry out the arcjet research using catalytic decomposition products of hydrazine as propellant, which is helpful for the development of engineering prototype and application in satellite.A kind of low power arcjet structure is designed, manufactured and combined in this thesis. An experimental platform was also built up. In vacuum environment, performance parameters of arcjet are systematically measured under different running conditions using nitrogen, hydrogen, ammonia, their mixtures (to simulate the catalytic decomposition products of hydrazine) as the propellants respectively. The performances of arcjet using nitrogen, hydrogen, ammonia and their mixtures with different proportion as propellant are compared, and the thruster performance under different proportion of the mixture components is analyzed. In the same propellant flux, the performance of the arcjet using ammonia as propellant is better than that of the arcjet using nitrogen as propellant, and the performance parameters changes of the arcjet using ammonia as propellant has the same characteristics with that of the arcjet using nitrogen as propellant. Therefore, ammonia is the propellant that will achieve higher performance, the mixture of nitrogen and ammonia with proper proportion could achieve fairly good performance. The larger is the proportion of ammonia in the mixture; the better is the performance of the arcjet. Additionally, the performance of the arcjet with or without the mixture propellant preheated is presented. Finally, the effects of different proportion of the mixture components and the preheated temperature of the propellant on the thruster performance are discussed.A new diagnostic system for arcjet plume is also established,by which the excitation temperature of arcjet using catalytic decomposition products of hydrazine as propellant was measured with spectrum. The excitation temperature and average excitation temperature are measured through absolute intensity method and Boltzmann diagram method. The experiment results show that the plume of the arcjet is in thermodynamic non-equilibrium state. Additionally, the influence of thermodynamic non-equilibrium state on the measurement results are discussed, and the effects of propellant components on the plume temperature are analyzed.