Anti-bombing insensitivity life of molybdenum cathode doped with La2O3 and Y2O3

Anti-bombing insensitivity of La2O3-Y2O3-Mo secondary emitter 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 HRM, SEM, EDS and XRD. The results showed that δmax of La2O3-Y2O3-Mo cathode operating at 1100 °C under continuous electron bombardment of 300 W/cm2 was still about 2.5 after 1000 h operation, indicating that this kind of cathode had good anti-bombing insensitivity. In the internal part of the cathode, RE2O3 (rare earth oxide) and molybdenum grains distributed alternately and there existed a certain relationship between crystallographic orientation of RE2O3 and that of molybdenum. It was found that a RE2O3 layer was formed on the surface after operation. The high δmax of La2O3-Y2O3-Mo cathode was related to the RE2O3 layer on the surface and the amount of nanosized La2O3 particles on the Y2O3 layer.