Influence Of Magnetic Lens On Wall Erosion Of Hall Effect Thruster

Hall thruster is an advanced electric thruster, used widely in the location maintainment of the satellite and attitude control, with the advantages of high efficiency, high specific impulse. It intrigues the world wide interests in the electric propulsion field. Recent years, as the high speed development of the astronautic techniques, the service life of the Hall thruster is required to be increased as well. In all erosion processes, the channel wall sputtering erosion is the most important problem that limits the service life of Hall thruster. The problem needs widely attention from Hall thruster technique researchers.The ion characteristic bombarding the walls can be controled effectively by altering the magnetic field topography. A good focusing magnetic field topography can effectively control the ions action in Hall thruster chamber, decreasing the angle of plume, enhancing the working ability, and notedly influencing the wall erosion. The thesis,the influence of magnetic lens on wall erosion of Hall thruster was studied by numerical simulations and experimental measurements. the main contents are as follows:Firstly, the work analyzed the principle of wall eosion, extracted the ion parameters that determine intensity of wall erosion from the erosion model. this chapter summarized the principle of magnetic lens in Hall thruster, the result indicated that the potential distribution in chamber could be changed by adjusting the magnetic field. The PIC(Particle in Cell) metheld was used to statistic the changing of ion parameters with magnetic field. The result showed that it's the density of incident ion beam that influenced clearly by degree of magnetic lens. Via observing the distribution of potential and the center of the ion density in chamber, it explained how the degree of magnetic lens effected the intensity of wall erosion. It simulated the evolution of the wall under different magnetic fields by Huygens method. It came to that a good magnetic structure could make the erosion intensity of internal and external wall at a low level.Secondly, the work found an experiment method to analyze the impact of magnetic lens on incidence ion beam parameters. When the degree of magnetic lens changed, the angle of plume, discharge current and utilization of mass changed as well. By sliting the external wall, a spot of ions were induced to outside of the chamber for measurement. The variation of ion paramenters were got by changing mangnetic field. The result coincided with numerical simulations. We found the method that measuring the erosion intensity by spectral. It comes to show that the spectral line intensity was very low at a good focursing magnetic lens. This could give a proof that the erosion is also at a low level.At last, a short time comparative experiment about wall erosion was carried out in both cases of good focursing and diverging magnetic field. The work analyzed the impact of magnetic lens on wall profile evolution and asymmetry of wall erosion. The result shows that the manner of wall profile evolution is stable when the magnetic field good focursing, while it evolves unsteadily when the magnetic field diverging. The magnetic lens can decrease the erosion rate of external angle, thereby,it heightens the lifetime of Hall thruster. The erosion rate of inner wall is greater than outer wall at different degree of magnetic lens. The work analysed the impact of design of magnetic pole, annular chamber and magnetic mirror effect on asymmetry erosion.