Research On The Dynamic Properties Of Thruster Plume Based On PIC-MCC Method

Due to its small size,high specific impulse,and long life,Hall thrusters are increasingly used in the propulsion missions of small satellites and deep space probes.In recent years,the research and development of Hall thrusters at home and abroad is moving in the direction of high power.As a kind of electric propulsion,the Hall thruster generates ions through electron ionization of neutral gas,and the ions are accelerated and ejected backward under the action of electric field force to produce reverse thrust.Therefore,it is necessary to study the nature and interaction of these plasmas in order to better design Hall thrusters with good performance.In addition,there is still a large amount of plasma in the plume area at a certain distance from the channel opening,and these plasmas are also called plumes.The nature of the Hall thruster plume is another key research topic in addition to the discharge performance of the Hall thruster.Plume,one is that ions and electrons interfere with the electromagnetic communication of the spacecraft;the other is that the neutralized electrons in the plume will sputter on the surface of the spacecraft,causing corrosion of the spacecraft;the third is that the high-energy particles in the plume and the surface of the spacecraft The interaction between them will produce interference torque,which will affect the operating state of the spacecraft in orbit.Assessing the interaction between the thruster plume and the spacecraft is a key configuration issue for determining the position of the thruster and other factors,and usually requires a trade-off between the pros and cons of thrust efficiency.The plasma movement process of the Hall thruster is relatively complicated,and the internal mechanism of many physical processes has not been clarified.Further exploration is needed for the plasma movement law of the Hall thruster.With the improvement of computer performance,the numerical simulation of Hall thruster plasma becomes possible.In this paper,the Particle in cell plus Monte Carlo collision(PIC-MCC)method is used to numerically simulate the Hall thruster plume.The PIC-MCC calculation program was developed through a deep understanding of the PIC-MCC algorithm.The programming thought and development process of the program are embodied in chapter two and chapter three.Magnetic field and electromagnetism are the basis of the plasma motion of the Hall thruster and an important factor affecting the performance of the Hall thruster.This article first calculates the magnetic field by the finite difference method,depicts the overall distribution of the magnetic field,and the configuration of the magnetic field.Secondly,in order to select the optimal magnetic field distribution,the distribution of the magnetic field under different currents was studied by changing the current of the excitation coil.Studies have shown that when the same current is applied to the inner and outer coils,the magnetic field is optimally distributed.At this time,the effective width of the magnetic field at the exit of the channel is larger,the intensity of the magnetic field in the channel is small,the Larmor radius of electron movement is smaller,and the electron drifts The speed is greater.Afterwards,on the basis of the optimal magnetic field,the influence of electric field on the thrust of Hall thruster was studied by changing the voltage of the anode and the cathode,and the research results were consistent with the experimental measurements.Finally,using COMSOL software to establish a three-dimensional simulation model of the Hall thruster magnetic field,it is found that the magnetic field distribution is consistent with the magnetic field distribution calculated by the finite difference method.