Study On Discharge Characteristics In Acceleration Zone Of Magnetically Shielded Hall Thruster

Since its application,the Hall thruster has been valued by various aerospace powers due to its high specific impulse,small size and high efficiency.However,the Hall thruster always has the problem of channel erosion,which greatly limits the life of the Hall thruster..After the concept of the self-magnetic shielding Hall thruster was put forward,the problem of the erosion of the channel of the Hall thruster was completely solved,and the service life of the Hall thruster was greatly improved.Magnetically shielded Hall thruster change the ionization and thrust zone position near the exit of the thruster channel with its unique magnetic field design.The ionization acceleration process is different from the traditional non-magnetic shielding thruster.The discharge characteristics of the thruster acceleration zone are of great significance for understanding the discharge mechanism of the magnetic shielded Hall thruster.This paper mainly studies from the following aspects:First of all,because the thruster used in this paper is the latest 1.5kW magnetic shielding Hall thruster designed by the research group,it is necessary to have a comprehensive understanding of the overall working performance of the thruster to study the discharge characteristics of the thruster acceleration zone.In this paper,the magnetic resonance characteristics,volt-ampere characteristic curve and flow-ampere characteristic curve of the thruster under different discharge voltages and anode flow rates are measured by the combination of Faraday probe and RPA probe.The difference between working performance and traditional non-magnetic shielding thruster.Through the study,the working performance of the thruster has been fully understood,and the optimal excitation working point of the thruster under 300 V discharge condition and the excitation range of stable operation are determined by the volt-ampere characteristic curve,which is the next experiment.Provided favorable conditions.Secondly,according to the experimental conditions determined by the performance comparison experiment,the Langmuir single probe was used to diagnose the discharge parameters of the acceleration zone.The probe diagnosis method in this paper is different from the foreign probe diagnosis method.The influence of beam current on probe measurement is discussed.According to the evaluation result,the probe collection surface is used to measure the plume.The effects of cathode position,cathode flow and magnetic field strength on the discharge parameters of the magnetically shielded Hall thruster acceleration zone are discussed during the measurement.Thirdly,the interaction between the plasma and the magnetic pole surface in themagnetic shielding Hall thrust acceleration region is studied.The specially designed planar single probe and Faraday probe are used to measure the plasma parameters of the magnetic pole surface.The distribution of plasma in the acceleration region at different cathode positions and cathode flow rates is compared,and the magnetic pole erosion is given.Speculative conclusion.In addition,for the surface coating of the magnetic pole,the interaction between the surface of the magnetic pole and the plasma of the acceleration region is studied.It is found that the magnetic pole coating can improve the erosion of the magnetic pole surface.Finally,the experimental phenomena measured in the experiment are explained microscopically by the PIC numerical simulation method.The simulation gives a reasonable explanation for the surface erosion of the magnetic shielding Hall thruster,and proposes that the magnetic shielding of the magnetic shielding thruster is the same physical mechanism as the non-magnetic shielding channel erosion,which proves that the surface of the ion bombarded magnetic pole is the main cause of magnetic pole erosion.the reason.In addition,the reason for the difference of plasma distribution on the surface of the magnetic pole after coating is given by numerical simulation for the magnetic pole coating experiment,and the influence of the magnetic pole coating on the internal magnetic pole erosion is further analyzed.