Y2O3掺杂压制钡钨阴极的制备及发射性能研究

摘要

A new kind of Y2 O3 doped Ba-W pressed cathode had been prepared by a sol-gel method combined with sintering tech-nique under hydrogen atmosphere.The thermionic emission and secondary electron emission properties of the cathode were test-ed,respectively.The results show that the particles of cathode powder prepared by the sol-gel method are uniform and small, which is favorable for full reaction between the tungsten substrate and aluminates during the sintering process to form the active substance.The measurements of emission performance show that the zero emission current density (J 0 )can reach 4.18 A/cm2 for the fully activated cathode at 1 050 ℃.The secondary electron emission coefficient increases with the increasing content of Y2 O3 ,and the maximum secondary electron emission coefficientδm of the cathode is 2.92.The analysis on the surface of the cathode indicates that the active elements Ba,Y and O can diffuse from the inner body to surface of the cathode to form a uniform distribution active layer during the activation process,,which can facilitate the emission property of the cathode.%通过溶胶凝胶法制备氧化钇、活性盐和钨均匀混合的前驱粉末，结合氢气高温烧结制备得到稀土氧化物 Y2 O3掺杂压制钡钨新型阴极材料，并分别测试其热电子发射性能和二次电子发射性能。试验结果表明，采用溶胶凝胶法制备的阴极粉末颗粒分布均匀且细小，在高温烧结过程中有利于活性盐与基体钨之间反应充分，从而形成有利于提高发射的活性物质。发射性能测试结果显示：激活良好的阴极在测试温度1050℃时的零场电流密度 J 0为4．18 A/cm2；二次电子发射系数随 Y2 O3含量增加而增大，最大二次电子发射系数δm 可以达到2．92。对阴极进行表面分析，激活过程中活性元素 Ba、Y 和 O 等从阴极内部向表面扩散，在表面形成均匀分布的发射活性层，促进了阴极的发射。