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采用粒子网格(Particle-In-Cell,PIC)方法对同轴微阴极电弧推力器(μCAT)工作过程进行了模拟研究,并应用自相似方法对模型进行简化,获得了推力器羽流区的电子数密度分布、离子数密度分布、电势分布及离子轴向平均速度,通过改变磁感应强度和位形分析磁场对推力器内等离子体运动特性及推力器性能的影响。计算结果表明,电子被外加磁场捕获约束在磁力线附近,低速离子与高速电子形成的双极扩散电场加速离子喷出;在相同流量情况下,磁感应强度0.02T时,离子返流严重,磁感应强度0.05~0.30T时,磁感应强度变化对速度影响较小;磁场位形对离子运动和推力器性能有较大影响,磁力线与轴线夹角较小时离子速度下降明显,夹角较大时离子返流严重。
The working process of coaxial micro-cathode arc thruster (μCAT) was simulated by Particle-In-Cell (PIC) method. The self-similarity method was used to simplify the model. Electron density distribution, ion number density distribution, potential distribution and the average velocity of ions in the axial direction. By changing the magnetic flux density and position analysis magnetic field, the influence of the magnetic field on the plasma characteristics and the performance of the thruster is analyzed. The calculated results show that the electrons are trapped in the vicinity of the magnetic flux by the applied magnetic field and accelerated by the bipolar diffusion electric field formed by the low-speed ions and the high-speed electrons. At the same flow rate, the ion backflow is severe with the magnetic flux density of 0.02T and the magnetic flux density is 0.05 ~ 0.30T, the change of magnetic flux density has little effect on the velocity; the magnetic field shape has a great influence on the ion motion and the performance of the thruster. The ion velocity drops obviously when the angle between the magnetic line and the axis is small. .