稀土钨基钡扩散型次级阴极研究

项目名称： 稀土钨基钡扩散型次级阴极研究

项目编号： No.51471006

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 王金淑

作者单位： 北京工业大学

项目金额： 85万元

中文摘要： 随着磁控管向着高功率和高频率方向发展，对阴极的发射性能提出了高要求。具有较好热发射和次级发射能力的阴极是电真空器件发展的关键。 本项目以稀土氧化物作为次级发射物质，Ba-O活性层提供热发射的新思路，研究制备稀土钨基钡扩散型次级阴极材料。建立真空晶胞模型，采用第一性原理计算方法优选稀土氧化物及复合稀土氧化物。通过液液掺杂技术制备稀土氧化物掺杂钨粉，研究其还原过程动力学，以期实现还原过程控制。研究烧结过程中稀土钨基微观结构变化行为及规律，为多孔钨基体的孔隙控制提供依据。采用热力学及动力学方法分别研究活性元素生成原理及其在阴极中的扩散机制。结合蒸发性能及蒸发过程动力学的研究，认识表面活性层形成机制及维持的动态平衡关系，探讨其发射稳定性与表面活性层之间的关系。研究稀土氧化物能带结构、晶面逸出功与发射性能的关系，讨论晶粒尺寸对次级电子发射模式的影响，为获得发射性能优异的阴极提供理论指导。

中文关键词： 阴极；钨；稀土掺杂

英文摘要： With the development of magnetrons towards high powder and high frequency, the cathodes which provide better thermionic property and secondary emission capability has become the key issue to meet the requirement of the vacuum electron devices. Based on the theoretical idea of using rare earth oxide (RE2O3) as the seconday emission materials and Ba-O active substance layer to provide the thermionic emission, RE2O3-W matrix Ba-dispenser secondary cathode will be developed in this work. The Rare earth oxide and rare earth oxide composites have been chosen through first princile calculation method based on the established vacuum cell model. RE2O3 doped W powder is prepared by liquid-liquid doping method. In order to control the reduction process, the reduction kinetics of RE2O3 doped WO3 will be studied. The change of the microstrucutre of the RE2O3-W matrix during the sintering period will be studied in order to get the ideal porous RE2O3-W body. The formation of active substance and its diffusion behavior will be studied by thermodynamic calculation and kinetics study, respectively. The formation and maintanience of the active substance layer on the cathode surface, an important issue to keep the emission stability, will be studied based on the evaporation behavior of these substance and kinetics of evaportion process. The correlation among the band structure of rare earth oxide, work function of different crystal plane and emission property will be discussed, togeter with the effects of grain size on the electron emission way. The above work will provide a theoretical guide for the development of novel cathode with good emission performance.

英文关键词： Cathode;Tungsten;Rare earth doping