Probe diagnosis of plume of micro-cathode arc thruster

Owing to the characteristics of low power and simple structure, micro-cathode arc thruster(i/CAT) meets the mission requirements of micro-nano satellites, and thus has a good development prospect. The diagnosis of //CAT plume can reveal the acceleration mechanism of the thruster, which is of great significance for improving the performance of liCAT. The electron temperature, electron density and ion velocity at different positions of liCAT 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 liCAT 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 liCAT 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.