Low-power Mpt Cavity To Improve The Design And Experimental Study

Microwave plasma thruster which is being studied is a new type of electric propulsion, so it has a potential demand to be developed. In MPT system, the microwave resonator is the important component, which is in charge of the gas propellant's absorbing and transforming the microwave energy, just like the combustion chamber in chemical propulsion. To develop a high efficient resonator is the key to all MPT system development.The research of this paper is based on the old resonator. The old one makes MPT approach to engineer application because of its small size. The structure of it is simple, the power apply to it is lower than 100W, the leakage of microwave is little, and it can ignite to start up on ground environment and in vacuum, can work by several kinds of propellant. Through the former experiments, low reliability in ignition and low efficiency in resonator are noticed, aimed to these two points, firstly, in consideration of the specialties of the concentrated capacitive coaxial resonator, the electromagnetic field in it and equivalent circuit of it are analyzed through the theory of transmission line and regular wave-guide, the transform of energy, the condition of resonance, the mode of excitation, the matching of impedance and the factor of quality are discussed. Secondly, considering the excitation probe and inner conductor's effect on the structure of field, the improved configuration of microwave resonator is designed through the theory of electromagnetic field and the method of microwave circuit and mechanism design, the material of resonator, the dimensions of main structure, the mode and device of excitation, the observing window, the nozzle and other structure are confirmed, the preferable structures of resonator is acquired.Lastly, in contrast to the old resonator, the ignition reliability and efficiency of the new one are experimented in atmosphere and vacuum environment respectively, which are aimed to validate the new one's performance. The results of the experiments show that the measures to improve the old resonator are effectual;the new one can start up to work reliably, the absorbing efficiency of energy in MPTresonator is increased to a certain extent.