Research On Cold Cathode Neutralization Electron Source Of Electric Thruster

With the continuous development of modern space technology,the types and USES of spacecraft are also increasing.Because of its good economic effect and the formation working mode with stronger working ability,the micro-nano satellite has gained more development and attention.Electric thruster is a continuously adjustable space propulsion device capable of generating N~mN thrust.It has the characteristics of high specific impulse,small thrust and long service life,which is very consistent with the in-orbit working requirements of micro-nano satellite.However,the plasma discharged by the electric thrusters may stick to the surface of the satellite,causing degradation of the satellite’s performance and other problems,which is known as plume pollution.In order to solve the plume pollution problem in the electric propeller,the micro-nano satellite urgently needs neutralizing electron source with small load,small volume,large emission current,low power consumption and long life to neutralize the positive ions.By molybdenum pointed cone field emission cathode array as a neutralizer electronic source,using finite element OPERA-3D electromagnetic field simulation software for the overall structure,the structure of the magnetic deflection system modeling and simulation,finally was simple in structure,emission stability,strong ability to resist pollution of electric propulsion cold cathode and electronic sources,and related tests.The main contents and conclusions are as follows:Design and preparation of cold cathode array: In order to obtain small volume and strong transmitting capacity of cold cathode emission substrates,the properties of hot cold cathode emission materials were analyzed,and the most suitable materials were selected.The structure of the transmitting array is designed,and the preparation technology and method of the internal gate type cathode transmitting array are analyzed.The effect of evaporation Angle and stripping time of sacrificial layer on the cone shape was discussed.Finally,the performance of the cathode array is tested and the emission capability of the cold cathode array is measured.Simulation and optimization of the structure of cold cathode neutralization electronic source: the electromagnetic field simulation software OPERA-3D was used to design and optimize the structure of neutralization electronic source;Aiming at the problem of cathodic anti-pollution,a method of magnetic deflection structure is proposed to avoid it.The structure of each part of the electron source is discussed,and the structure design parameters with good electron beam trajectory are obtained.Assembly and testing of cold cathode and neutralization electronic source: design parts according to simulation results,process and assemble test circuit,put forward reliable test method,and analyze the errors in actual use.Finally,A device with an overall size of 28mm×28mm was obtained.When providing 800 V anode voltage and 120 V gate voltage,512μA living current could be obtained,and the cold cathode with an electron beam deflection trajectory of almost 90° would neutralize the electron source.