浸渍钡钨阴极蒸发性能的AES分析

利用俄歇能谱就地定性、定量地测量了浸渍钡钨阴极(4.56∶1.44∶2)的蒸发成分和速率。得到的主要结果是:(1)老炼初期和寿命初期蒸发率可相差半个量级,前者的蒸发能为4.34eV,而后者为4.58eV;(2)蒸发物成分随阴极温度不同而变化,高温激活时,氧化钡在蒸发物中的比例缓慢减少,但Ca的蒸发增加,1250℃时,约占3.5％,在工作温度范围内,90％左右为金属钡,氧化钡约占9.3％;(3)与50年代蒸发测量相比,AES法得到的BaO蒸发量少得多,但与热力学理论计算的结果一致;(4)与AES计量的5∶3∶2,4∶1∶1阴极相比,所研究的阴极(4.56∶1.44∶2)的Ca蒸发量少得多,这是该阴极的特点;(5)逸出功测量和AST曲线都表明,当吸附了约1.51014at./cm2的钡时,多晶钨表面已建立一个由吸附原子形成的均匀的屏蔽场。

RESEARCH ON THE EVAPORATION PROPERTY OF IMPREGNATED DISPENSER CATHODE BY AES

During the activation and aging, the evaporation components and rates from 4.56:1.44:2 impregnated dispenser cathode have been determined by the vapor-collect method based on AES. (1) the evaporation rate of a cathode after aging differs from that of a just activated cathode by a factor of 5 to 10. The evaporation energy of the former is 4.58 eV, and that of the latter is 4.34 eV. (2) at operating temperatures, the metallic Ba in the evaporated material is about 90%, and the barium oxide is about 9.3%. (3) below 1000℃ the evaporation of Ca is not significant, over 1150℃ the Ca starts evaporating rapidly, particularly in the activation process, it may approach 3.5% at 1250℃.