La-Mo阴极发射性能及机理研究

研究了实用型La-Mo电子管的发射性能,并采用热力学计算、原位XPS等方法对La-Mo阴极中La的价态进行了研究,探讨了该阴极的发射机理。实验结果表明,实用型FU6051 La-Mo电子管的阴极饱和脉冲电流密度为同型号钍钨管的2.32倍,而所需加热功率仅为钍钨阴极的47%。高温下La2O3可以被Mo2C还原成单质La。在阴极工作过程中,还原得到的La覆盖在Mo基体表面,降低了基体Mo的逸出功,促进了阴极的发射。

A Study of the Emission Property and Mechanism of La-Mo Cathode

The emission property of La-Mo commercial tube and the emission mechanism of this kind of cathode have been studied.The valence of element lanthanum of cathode material has been studied by using thermodynamic calculation,in-situ high temperature X-ray photoelectron spectrum.On the basis of experiment results,the emission mechanism of La-Mo cathode has been discussed.Experimental results show that the saturated pulse emission current of La-Mo FU6051 electronic tube is about 2.32 times higher than that of Th-W tube,and the heating power is only 47% of Th-W tube.It has been proved that molybdenum carbide can reduce lanthanum oxide to metallic lanthanum.It is shown that it is the formation of a monatomic layer of metallic lanthanum at the surface of a filament that is the cause of the emissivity of the cathode since the monatomic active surface layer has a lower work function than clean molybdenum.