Study on Secondary Emission Properties of the Molybdenum Cathode Doped with Ln₂O₃

In order to research and develop a kind of ideal cathode material so as to replace the existing Ba-W and Th-W cathodes used in magnetron, the powder metallurgy method was adopted to prepare the cathod material of substrate molybdenum doped with Ln₂O₃ in different proportion. The secondary emission coefficients of all the materials were also tested. The results show that the secondary emission properties of the doped cathode material are much higher than that of pure molybdenum cathode; The secondary emittor doped with composite rare-earth oxides is better than that with elementary rare-earth oxides in emission property. In addition, scanning electronic microscopic (SEM) and Auger electronic spectrum (AES) were employed to study the distribution of rare-earth elements at/ on the fracture and surface of molybdenum sinter. The analysed results show that rare-earth tends to gather at grain boundaries and the relevent concentration of rare-earth on the surface of sample is obviously higher than that in the interior of the material.