Effect Of Zero Magnetic Field And Channel Width On Hall Thruster Discharge Characteristics

Hall thruster is an electric propulsion device that is widely used in space propulsion tasks.It has the advantages of high specific impulse,long life and good reliability.In order to meet different types of space propulsion tasks,electric propulsion technology has been continuously innovating and developing.Hall thruster magnetic field configuration and channel width are important factors affecting thruster performance,and its influence mechanism on thruster needs to be further explored.In this paper,a particle simulation method is used to establish a two-dimensional physical model for the discharge channel of the ATON P70 Hall thruster.The effects of the zero magnetic field region and the channel width of the Hall thruster on the plasma discharge characteristics are studied.It provides reference to the design of magnetic field configuration and the selection of channel width of thruster.Based on the establishment of a two-dimensional physical model of the thruster channel discharge,the magnetic field model is designed by FEMM software to obtain the magnetic field configuration at different zero magnetic point positions.The influence of magnetic field configuration on the parameters of thruster,such as ion number density,space potential,ion radial velocity,electron temperature,ionization rate and specific impulse,is studied by Particle-in-cell method.The results show that when the position of the zero magnetic point on the central axis of the discharge channel moves from the anode to the channel exit direction,the ion number density increases,the ion radial velocity decreases,and the specific impulse increases.When the zero magnetic point changes radially from the inner wall surface to the outer wall surface,the ionization zone also moves radially,and the specific impulse of thruster first decreases and then increases.When the position of the zero magnetic point is close to the inner wall surface,the collision frequency of the ion wall surface decreases,and the specific impulse of the thruster is maximum.Reduce the inner diameter of the wall surface of the thruster magnetic field model by FEMM software,and the permanent magnet material is used to replace the electromagnetic coil.The results show that with the increase of working fluid flow,the electron density,ionization rate and potential peak value of the two channel width increase gradually,the electron gathering area increases and expands towards the exit of the channel,the potential drop compresses towards the exit,the range of ionization rate narrows,and the ionization area concentrates.When the working fluid flow rate is high(3.5 mg/s?4.5 mg/s),the electron temperature and ionization rate of wide channel increase obviously,the radial velocity of ions is reduced,the wall corrosion is weakened,and the life of the thruster is extended.For discharge channels of permanent magnetic materials,the changes of performance parameters such as discharge current,specific impulse,collision frequency and thrust power ratio of the thruster with different channel widths and working fluid flow are numerically studied.The results show that the discharge current and specific impulse of different channel widths increase with the increase of working fluid flow.When the value of the working fluid flow is 2 mg/s?3.5 mg/s,with the increase of the working fluid flow,the collision frequency of ions of the wide channel(r=18 mm)with the wall surface increases,and the collision frequency of electrons with the wall surface is proportional to the working fluid flow When the flow rate of the working medium is 4 mg/s,the wide channel thrust power ratio reaches the maximum value and thruster performance improved.