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It is shown from the experimental results of existing Hall thrusters that erosion phenomena occur in the magnetic poles when the maximum magnetic field is located in the plume region. The developed Particle-in-Cell model is used in this paper for simulation research on magnetic pole erosion of Hall thrusters. The simulation results show that when the maximum magnetic field is located in the plume region, there is a large potential drop between the channel outlet and the magnetic pole. Therefore, low-energy ions close to the outlet plane are accelerated to bombard the magnetic pole surface, which is an important reason for the magnetic pole erosion. Moreover, the ion flux and energy bombarded on the magnetic pole under two conditions (magnetic pole grounding and floating) are calculated and compared. It is shown from the simulation results that grounding the magnetic pole can reduce the potential drop between the channel outlet and magnetic pole, thereby reducing the ion energy and flux bombarded on the magnetic pole and effectively alleviating the erosion of the magnetic pole. [ABSTRACT FROM AUTHOR]

The structure of an azimuthal diversion rail causes the neutral gas in the Hall effect thruster to possess a certain circumferential velocity. Two different directions of the magnetic field can be formed in the discharge channel, where the direction of the magnetic field depends on the direction of the excitation current. The aim of this work is to study the effect of magnetic field directionality on the discharging characteristics of a Hall effect thruster with an azimuthal diversion rail. The experimental results demonstrate that a change in the magnetic field direction corresponds to a change in the electronic Hall drift direction. When the electronic Hall drift direction is opposite to the circumferential velocity of the neutral gas, its thrust, specific impulse, and efficiency are higher than the case in which the electronic Hall drift direction is in the same direction as that of the circumferential velocity of neutral gas. The increase in performances is due to the increase in the propellant utilization. The reasons for the increase in the propellant utilization are explained. The experimental result provides a guide for the selection of the direction of excitation current of the Hall effect thruster with an azimuthal diversion rail. [ABSTRACT FROM AUTHOR]

In order to increase the degree of ionization and improve the efficiency, the effects of different cylindrical outer wall lengths on the discharge characteristics of the annular-cylindrical combined channel Hall thruster are studied. The cylindrical outer wall is set to the following positions: 95% (with positive magnetic field gradient), and 100%, 95%, 90%, 75%, and 50% (with negative magnetic field gradient) of the maximum magnetic field. The ionization gain and wall energy loss under different positions are analyzed through numerical simulations. The simulation result shows that when the cylindrical outer wall is set to the position where it is 100%–90% of the maximum magnetic field (negative magnetic field gradient zone), the power deposition on the channel wall is small, the propellant utilization can be largely improved, and the comprehensive performance is optimal for the annular-cylindrical combined channel Hall thruster. [ABSTRACT FROM AUTHOR]

The strength and shape of the magnetic field are the core factors in the design of the Hall thruster. However, Hall current can affect the distribution of static magnetic field. In this paper, the Particle-In-Cell (PIC) method is used to obtain the distribution of Hall current in the discharge channel. The Hall current is separated into a direct and an alternating part to calculate the induced magnetic field using Finite Element Method Magnetics (FEMM). The results show that the direct Hall current decreases the magnetic field strength in the acceleration region and also changes the shape of the magnetic field. The maximum reduction in radial magnetic field strength in the exit plane is 10.8 G for an anode flow rate of 15 mg/s and the maximum angle change of the magnetic field line is close to 3° in the acceleration region. The alternating Hall current induces an oscillating magnetic field in the whole discharge channel. The actual magnetic deformation is shown to contain these two parts. [ABSTRACT FROM AUTHOR]