微阴极电弧推力器羽流探针诊断研究

微阴极电弧推力器（micro-cathode arc thruster，μCAT）具备功率低和结构简单的特点，能够满足微纳卫星的任务需求，具有良好的发展前景。μCAT羽流的诊断可以揭示推力器的加速机理，对提高其性能具有重要意义。利用朗缪尔三探针对μCAT羽流进行诊断，得到了μCAT羽流不同位置的电子温度、电子密度和离子速度等羽流特性，研究了外加磁场、充电时间和阴极材料对羽流特性的影响。研究结果表明，μCAT放电初期产生的等离子体电子温度较高，密度较大；随着等离子体向下游运动，电子温度和电子密度降低，离子速度增大；外加磁场的磁感应强度越强，电子温度和离子速度越高，电子密度有所降低；磁场位置适当向推力器下游平移，能够有效提高推力器中轴线的电子密度；μCAT充电时间越长，电子温度、电子密度和离子速度越大；相比于CuW和AgW阴极，Ti阴极羽流的电子温度更高，电子密度更低。

Probe diagnosis of plume of micro-cathode arc thruster

Owing to the characteristics of low power and simple structure，micro cathode arc thruster（μCAT）meets the mission requirements of micro-nano satellites，and thus has a good development prospect.The diagnosis of μCAT plume can reveal the acceleration mechanism of the thruster，which is of great significance for improving the performance of μCAT.The electron temperature，electron density and ion velocity at different positions of μCAT plume were obtained by using Langmuir three probe.The effects of external magnetic field，charging time and cathode material on plasma characteristics and ion velocity were investigated.The results show that the plasma generated at the initial stage of μCAT discharge has the characteristics of higher electron temperature and density.As the plume moves downstream，electron temperature and electron density decrease，and ion velocity increases.With the stronger external magnetic field，electron temperature and ion velocity increase，and electron density decreases.The electron density of the central axis of thruster is improved effectively when the external magnetic field is shifted to the downstream of thruster.As the charging time of μCAT is longer，the electron temperature，electron density and ion velocity increase.Compared with CuW and AgW cathodes，the electron temperature of Ti cathode plume is higher and electron density is lower.