Effect of anode magnetic shield on inner magnetic pole etched in anode layer Hall thruster

Abstract

For anode layer Hall plasma thruster, the etching of inner magnetic pole is one of the key factors affecting its service life. In order to solve the problem of inner magnetic pole etching in anode layer Hall plasma thruster, the effect of anode magnetic shield on inner magnetic pole etched in anode layer Hall thruster is studied by combining particle simulation PIC with sputtering simulation. The magnetic shielding of anode changes the distribution of magnetic field configuration on the surface of the anode, and improves the magnetic mirror ratio of the magnetic mirror field of the thruster to the magnetic field width of the positive gradient on the central axis. The ratio of the magnetic mirror is 1.4 times that of the original one, and two additional saddle magnetic fields are added on both sides of the original saddle magnetic field region. It not only is conducive to confining electrons and improving the ionization rate of working gas, but also keeps a certain distance between the anode and the high temperature electron region, which provides the reliable reference data for the design of high power Hall plasma thruster. When the discharge voltage is 900 V and the working pressure is 2 × 10<sup>–2</sup> Pa, the simulation results show that after the anode is shielded by the magnetic shield, the energy range of most of the incident ions on the inner magnetic pole is 40–260 eV, which is 100 eV lower than the energy range 40–360 eV in the case without shielding the anode. The probability distribution of particle energy without magnetically shielding the anode between 260 eV and 600 eV is obviously higher than that of ion energy with magnetically shielding the anode. The maximum probability distribution of cosine value of incident angle is extended from a small range near 0.1 (incident angle 84°) to a large range of 0.1–0.45 (incident angle 84°–63°). The magnetic shielding makes the incident ions disperse on the surface of the inner magnetic pole, which is helpful in reducing the etching of inner magnetic pole. The maximum etching rate of inner magnetic pole after the anode has been magnetically shielded is reduced from 16 × 10<sup>–10</sup> m/s to 6.1 × 10<sup>–10</sup> m/s, which is 2.62 times lower. The comparison of simulation results with experimental results in the case without magnetically shielding the anode shows that they are in good agreement.