Study On Effect Of Channel Wall Material Arrangement And Magnetic Field On Hall Thruster Discharge Characteristics

Hall thruster is an advanced electric thruster,with high efficiency,high precision,high specific impulse,etc.,widely used in various spacecraft promote missions.The optimal arrangement of the wall material of the Hall thruster discharge channel will affect the physical process of the plasma in the channel,and the magnetic field intensity and configuration can restrain the electric conductivity and control the potential distribution of the thruster,thus affecting the Hall thruster performance.Because of the strong interaction between the discharge channel plasma and the wall,its physical mechanism needs further exploration.Therefore,it is very important to study the channel wall material layout and magnetic field optimization of Hall thruster.In this paper,a 2-D axial symmetry physical model is established based on the Hall thruster structure,the effect of the segmenting high emissive silicon carbide material at the channel exit on the discharge characteristics of the thruster is numerically simulated by particle-in-cell simulation method.The results show that the segmentation of high emissive silicon carbide at the exit of the channel reduces the radial potential drop and the radial velocity of ion at the exit,thus reduces the wall corrosion.With the increase of the segmented length,the collision frequency of the electrons and the wall and ionization rate gradually increase,the electron temperature decreases gradually and the specific impulse increases slightly.The discharge current rises abruptly when the segmented length reaches 5 mm.Moreover,comparing with results of the segmented low emissive insulating wall,the discharge current of the high emissive insulating wall is relatively small and the efficiency is high when the segmented length is 3 mm.Using the magnetic field configuration of ATON Hall thruster,the effect of magnetic field intensity on the plasma physical process is studied numerically with constant the magnetic field configuration.The results show that the magnetic field cannot restrain the axial conduction of the electrons well when the maximum magnetic field intensity of the central axis is less than 0.020 T,leading to ionization mainly near the anode.When the maximum magnetic field intensity of the central axis of the thruster is greater than 0.020 T,with the increase of the magnetic field intensity,the electron temperature,the ionization rate and the electron-wall collision frequency decrease gradually,ion radial velocity gradually increases,the discharge current decreases firstly and then increases,and the thrust is basically the same.When the maximum magnetic field intensity of the central axis in the thruster is 0.028 T,the acceleration region is the shortest and the discharge current is the smallest.The effect of the magnetic field configuration on the plasma discharge characteristics of the Hall thruster channel is numerically simulated by changing the magnetic field configuration of the thruster.The results show that the magnetic field configuration perpendicular to the wall near the anode confines the electrons,the ionization region is compressed to the anode,resulting in sharp reduction of the discharge current and the thruster cannot sustain discharge.The location of the zero magnetic field region will affect the location of the ionization zone and ionization rate.when the zero magnetic field is located in the channel near the inner wall,the discharge current increased significantly,uneven distribution of electric potential at inner and outer wall of the discharge channel exit leads to a larger radial velocity of the ion at the outer wall and an increase in wall corrosion.