Effects of magnetic conduction ring on the discharge characteristics and the inner cover erosion of a 100 W Hall thruster

To address the high cost of adjusting the magnetic field near the inner cover of a permanent magnet Hall thruster, this paper proposes a magnetic conduction ring made of pure iron that allows for flexible adjustment of the magnetic field near the inner cover. Based on this, the study explores the effects of the magnetic conduction ring on the inner cover erosion and discharge characteristics of a 100 W permanent magnet Hall thruster. The experimental results show that the designed magnetic conduction ring can reduce the central magnetic field intensity at the upper surface of the inner cover by about 40 % and the central erosion rate of the cover by about 64 %, which greatly improves the service life of the cover. Meanwhile, the magnetic conduction ring will also cause the discharge performance of the thruster to decrease. Under the rated discharge conditions (anode voltage at 300 V, and anode power at 100 W), the anode efficiency will decrease by about 2.5 % (absolute value). Further studies have shown that the magnetic conduction ring causes the ionization and acceleration regions to shift downstream with the characteristic magnetic field, resulting in lower ion current density and energy in the plume. This is the primary reason for the discharge performance decline. The deterioration of the ionization process reduces the density of low-energy ion near the channel exit, which decreases the ion density sputtering the cover, thereby reducing erosion.