| The metal plasma thruster is an electric thruster that uses the metal plasma produced by vacuum arc ablating cathode metal material as the thrust source.It has the characteristics of small size,light weight and high reliability.However,at present,the ejection performance of the plasma source generated by vacuum discharge is poor,including low plasma density and low kinetic energy,resulting in relatively small thrust formed by the propeller,and practical application is limited.Therefore,it is of great significance to study new and efficient metal plasma thrusters and explore new propulsion methods that can effectively improve plasma characteristics and propulsion performance.This research mainly takes the metal plasma thruster as the research object,and uses theoretical analysis,methods of simulation and design experiments to explore the influence of the anode characteristics of the thruster on the discharge characteristics,plasma generation characteristics and propulsion performance.First,three types of discharge circuits with anode resistance,anode inductance and anode capacitance are designed,and Matlab / Simulink simulation software is used to simulate the discharge process of the three discharge circuits,and finally,the thrust force and thrust-power ratio are measured by the thrust force measurement system based on the PVDF piezoelectric film sensor,to explore the influence of anode electrical parameters.Results show that in vacuum pulse discharge,the absorption of anode charged particles can be controlled in time by changing the anode electrical parameters,which affects the establishment of cathode Hump,so that more charged particles are ejected along the axial direction of the nozzle of the insulating sleeve,and the ejection performance and propulsion performance of plasma jet is effectively improved.In particular,compared with the direct grounding of the anode of traditional thruster,the thrust peak value and the peak thrust power ratio generated by the thruster using the anode capacitance discharge circuit(C=100pF)are increased by 7 times and 9.4 times,respectively.Secondly,in order to fundamentally increase the amount of plasma generated and increase the thrust of the thruster,a method of applying voltage to the cathode and anode at the same time is proposed,and the influence of the anode potential amplitude and the anode potential polarity is discussed.The results show that applying pulse voltage on the cathode side and DC voltage on the anode side can maintain the electrode discharge for a long time,and the plasma continues to be generated,which fundamentally increases the amount of plasma.The positive potential of the anode can continuously accelerate the plasma,which improves the energy of the plasma jet.Compared with the traditional method of applying power on only one side of the electrode,the use of DC power on the other side at the same time increases the thrust peak value generated by the thruster from μN to mN.Finally,based on the structure of the insulated anode electrode,a vacuum pulse discharge experiment of multiple electrodes under one power supply is carried out,and the influence of electrode spacing and capacitance capacity is analyzed and studied.Results show that because the discharge voltage of the insulated anode structure decreases to the arc sustaining voltage after a period of time,the simultaneous discharge of multiple electrodes can be realized.Simultaneous discharge of multiple electrodes can increase the amount of plasma generation.The propulsion performance of the multi-electrode thruster is better than that of the single-electrode thruster,and the peak thrust and the peak thrust power ratio are increased by 2 times and 2.4 times,respectively. |
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