(北京工业大学 新型功能材料教育部重点实验室， 北京 100022)
摘 要: 从理论上计算了碳化Mo-La2O3热阴极材料在不同温度下活性物质镧元素的蒸发速度，分析了镧元素蒸发对材料热电子发射及其稳定性的影响。 计算结果表明： 当温度为1623~1700K时，阴极中镧的扩散速度大于阴极表面镧的蒸发速度， Mo-La2O3阴极表面单质La的生成和蒸发保持平衡， 阴极发射稳定； 当工作温度超过1700K， 阴极表面镧的蒸发速度超过扩散速度，发射电流逐渐减少。 测试了Mo-La2O3阴极FU-6051电子管在不同温度时的发射性能， 热力学理论计算结果较好地解析了实验结果。
关键字: Mo-La2O3热阴极; 热电子发射; 稳定性; 蒸发; 扩散
（The key Laboratory of Advanced Functional Materials,
Ministry of Education,
Beijing University of Technology, Beijing 100022, China）
Abstract: The evaporation rate of element La at different temperatures in carbonized Mo-La2O3 cathode were calculated according to thermodynamics theory. The results show that the diffusion rate is greater than the evaporation rate of La on cathode surface at the temperature range of 1623-1700K, so the formation and evaporation of La can remain balance and the emission current is stable, and that when the operating temperature is above 1700K, the evaporation rate of La exceeds its diffusion rate on the cathode surface so that the emission current decreases gradually. In addition, the emission properties of the FU-6051 tubes equipped with Mo-La2O3 cathodes were tested at different temperatures, and the experimental results confirme the thermodynamic calculation.
Key words: Mo-La2O3 heated cathode; thermionic electron emission; emitting stability; evaporation; diffusion
