Numerical Simulation for One Dimensional Steady Quasineutral Hybrid Model of Stationary Plasma Thruster

Based on the analysis of the physical mechanism of the Stationary Plasma Thruster （SPT）, an integral equation describing the ion density of the steady SPT and the ion velocity distribution function at an arbitrary axial position of the steady SPT channel are derived. The integral equation is equivalent to the Vlasov equation, but the former is simpler than the latter. A one dimensional steady quasineutral hybrid model is established. In this model, ions are described by the above integral equation, and neutrals and electrons are described by hydrodynamic equations. The transferred equivalency to the differential equation and the integral equation, together with other equations, are solved by an ordinary differential equation （ODE） solver in the Matlab. The numerical simulation results show that under various circumstances, the ion average velocity would be different and needs to be deduced separately.

Influence of channel length on discharge performance of anode layer Hall thruster studied by particle-in-cell simulation

Hall thruster has the advantages of simple structure, high specific impulse, high efficiency, and long service life, and so on. It is suitable for spacecraft attitude control, North and South position keeping, and other track tasks. The anode layer Hall thruster is a kind of Hall thruster. The thruster has a longer anode area and a relatively short discharge channel. In this paper, the effect of the channel length on the performance of the anode layer Hall thruster is simulated by the PIC simulation method. The simulation results show that the change of the channel length has significant effect on the plasma parameters, such as potential and plasma density and so on. The ionization region mainly concentrates at the hollow anode outlet position, and can gradually move toward the channel outlet as the channel length decreases. The collision between the ions and the wall increases with the channel length increasing. So the proper shortening of the channel length can increase the life of the thruster. Besides, the results show that there is a best choice of the channel length for obtaining the best performance. In this paper, thruster has the best performance under a channel length of 5 mm.

Particle-in-cell simulation for different magnetic mirror effects on the plasma distribution in a cusped field thruster

Magnetic mirror used as an efficient tool to confine plasma has been widely adopted in many different areas especially in recent cusped field thrusters. In order to check the influence of magnetic mirror effect on the plasma distribution in a cusped field thruster, three different radii of the discharge channel(6 mm, 4 mm, and 2 mm) in a cusped field thruster are investigated by using Particle-in-Cell Plus Monte Carlo(PIC-MCC) simulated method, under the condition of a fixed axial length of the discharge channel and the same operating parameters. It is found that magnetic cusps inside the small radius discharge channel cannot confine electrons very well. Thus, the electric field is hard to establish. With the reduction of the discharge channel’s diameter, more electrons will escape from cusps to the centerline area near the anode due to a lower magnetic mirror ratio. Meanwhile, the leak width of the cusped magnetic field will increase at the cusp. By increasing the magnetic field strength in a small radius model of a cusped field thruster, the negative effect caused by the weak magnetic mirror effect can be partially compensated. Therefore, according to engineering design, the increase of magnetic field strength can contribute to obtaining a good performance, when the radial distance between the magnets and the inner surface of the discharge channel is relatively big.

Research of influence of the additional electrode on Hall thruster plume by particle-in-cell simulation

Hall thruster is an electric propulsion device for attitude control and position maintenance of satellites.The discharge process of Hall thruster will produce divergent plume.The plume will cause erosion,static electricity,and other interference to the main components,such as solar sailboard,satellite body,and thruster.Therefore,reducing the divergence of the plume is an important content in the research of thruster plume.The additional electrode to the plume area is a way to reduce the divergence angle of the plume,but there are few related studies.This paper uses the particle-in-cell(PIC)simulation method to simulate the effect of the additional electrode on the discharge of the Hall thruster,and further explains the effect mechanism of the additional electrode on parameters such as the electric field and plume divergence angle.The simulation results show that the existence of the additional electrode can enhance the potential near the additional position.The increase of the potential can effectively suppress the radial diffusion of ions,and effectively reduce the plume divergence angle.The simulation results show that when the additional electrode is 30 V,the half plume divergence angle can be reduced by 18.21%.However,the existence of additional electric electrode can also enhance the ion bombardment on the magnetic pole.The additional electrode is relatively outside,the plume divergence angle is relatively small,and it can avoid excessive ion bombardment on the magnetic pole.The research work of this paper can provide a reference for the beam design of Hall thruster.

Particle-in-cell simulation for the effect of magnetic cusp on discharge characteristics in a cylindrical Hall thruster

The cylindrical Hall thruster has the good prospect of serving as a miniaturized electric propulsion device.A 2 D-3 V particle-in-cell plus Monte Carlo（PIC-MCC） method is used to study the effect of the magnetic cusp on discharge characteristics of a cylindrical Hall thruster.The simulation results show that the main ionization region and the main potential drop of the thruster are located at the upstream of the discharge channel.When the magnetic cusp moves toward the anode side,the main ionization region is compressed and weakened,moving upstream correspondingly.The ionization near the cusp is enhanced,and the interaction between the plasma and the wall increases.The simulation results suggest that the magnetic cusp should be located near the channel exit.

Low-frequency oscillations in Hall thrusters

In this paper, we summarize the research development of low-frequency oscillations in the last few decades. The findings of physical mechanism, characteristics and stabilizing methods of low-frequency oscillations are discussed. It shows that it is unreasonable and incomplete to model an ionization region separately to analyze the physical mechanism of low-frequency oscillations. Electro-dynamics as well as the formation conditions of ionization distribution play an important role in characteristics and stabilizing of low-frequency oscillations. Understanding the physical mechanism and characteristics of low- frequency oscillations thoroughly and developing a feasible method stabilizing this instability are still important research subjects.