激活后发射良好的Mo La2 O3 阴极表层含有大量镧 ,原子浓度比约为 (稍大于 )10 % ;发射衰减的阴极表层中镧含量减少 ,未激活的原始阴极丝表层中镧更少。对不同状态阴极中氧含量及其变化的比较 ,以及碳、钼峰分析认为 :发射良好阴极中镧的活性程度较大 ,即超额镧的存在是影响阴极工作性能的主要因素 ;衰减后阴极中镧的总量虽不小 ,但镧的活性显著降低是阴极发射不好的主要原因 The activated La LaO3 cathode layer contains a large amount of lanthanum after the activation, and the atomic concentration ratio is about (slightly larger than) 10%. The emission of the decayed cathode surface layer is reduced, and the surface layer of the original cathode wire is less activated. Comparison of oxygen content and its change in different states of cathode, as well as the analysis of carbon and molybdenum peak shows that the activity of lanthanum in cathode is good, that is, the existence of excess lanthanum is the main factor affecting cathode performance; Although the total amount of lanthanum is not small, but lanthanum significantly reduced activity is the main reason for poor cathode emission