A study on the anti-electron-bombing life of La2O3–Y2O3–Mo cermet cathode materials

Anti-bombing insensitivity of La2O3–Y2O3–Mo cermet cathode material has been studied in this paper. The variation of maximum secondary emission coefficient δmax with time was measured. The cathode after life experiment was analyzed by means of SEM, EDS and XRD. The results showed that δmax of La2O3–Y2O3–Mo cermet cathode operating at 1100 °C under continuous electron bombardment of 300 W/cm2 reached the maximum 3.35 at 200 h, and then decreased gradually. After bombardment for 500 h, the maximum secondary electron yield remained nearly the same. The δmax of La2O3–Y2O3–Mo cermet cathode was still about 2.5 after 1000 h operation, indicating that this kind of cathode had good anti-bombing insensitivity. The high δmax of La2O3–Y2O3–Mo cathode was related to the rare earth oxide layer on the surface at the high temperature and the amount of nanosized La2O3 particles on the Y2O3 layer. The decrease of the amount of La2O3 in the surface layer and pores in the cathode produced by the evaporation of MoO2 which is the oxidation product of Mo, led to the decrease of δmax.