磁路温度对霍尔推力器放电热稳定性的影响

Effects of Magnetic Circuit Temperature on Discharge Thermal Stability of a Hall Thruster

为研究磁路高温性质变化对霍尔推力器放电热失稳的贡献及影响机理,对不同磁路温度下推力器的工作磁场强度开展了实验测量,对磁路温度变化与通道内等离子体放电行为变化的交互影响开展了Particle-in-Cell数值模拟研究。实验结果表明,当磁路温度由室温升高到600℃时,推力器的工作磁场强度发生了衰减,尽管衰减量不大(约5%)。模拟结果表明,磁路高温引起的场强衰减改变了推力器放电时的电导率及电势分布,进而对电子能量各向分布、粒子密度分布等造成了影响,促进了电子在壁面的通量及能量损失,主导了壁面等离子体沉积功率的增加,从而进一步加剧了磁路温度的增长。这是一个具有正反馈性质的过程;因此,若不能通过外部手段有效控制磁路温度,将诱发霍尔推力器的放电热失稳。

In order to clarify the effects and intrinsic mechanism of high magnetic circuit temperature on the thermal discharge instability of a Hall thruster,an experimental study on the working magnetic field intensity of the thruster at different magnetic circuit temperature was carried out. Meanwhile,a Particle-in-Cell simulation was performed on the interaction between the change of magnetic circuit temperature and the change of plasma discharge behavior. The experimental results show that when the magnetic circuit temperature rises from room temperature to 600℃,the working magnetic field intensity of the thruster is attenuated despite that the attenuation is not significant（about 5%）. The simulation results show that the attenuation of magnetic field intensity,caused by the high magnetic circuit temperature,changes the distribution of electron cross-field mobility as well as electric potential,and consequently impacts the distributions of electron energy,particle density,and et al.As a result,both the flux and the energy that electrons loss on the channel walls are promoted,which dominates the variation of total deposition power and thus exacerbates the increase of magnetic circuit temperature. This is a process with a matter of positive feedback,therefore,if the magnetic circuit temperature cannot be controlled effectively,the thruster discharge would be unstable.