浸漬鋇鎢陰極蒸發(fā)性能的AES分析
RESEARCH ON THE EVAPORATION PROPERTY OF IMPREGNATED DISPENSER CATHODE BY AES
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摘要: 利用俄歇能譜就地定性、定量地測量了浸漬鋇鎢陰極(4.56∶1.44∶2)的蒸發(fā)成分和速率。得到的主要結(jié)果是:(1)老煉初期和壽命初期蒸發(fā)率可相差半個(gè)量級,前者的蒸發(fā)能為4.34eV,而后者為4.58eV;(2)蒸發(fā)物成分隨陰極溫度不同而變化,高溫激活時(shí),氧化鋇在蒸發(fā)物中的比例緩慢減少,但Ca的蒸發(fā)增加,1250℃時(shí),約占3.5％,在工作溫度范圍內(nèi),90％左右為金屬鋇,氧化鋇約占9.3％;(3)與50年代蒸發(fā)測量相比,AES法得到的BaO蒸發(fā)量少得多,但與熱力學(xué)理論計(jì)算的結(jié)果一致;(4)與AES計(jì)量的5∶3∶2,4∶1∶1陰極相比,所研究的陰極(4.56∶1.44∶2)的Ca蒸發(fā)量少得多,這是該陰極的特點(diǎn);(5)逸出功測量和AST曲線都表明,當(dāng)吸附了約1.51014at./cm2的鋇時(shí),多晶鎢表面已建立一個(gè)由吸附原子形成的均勻的屏蔽場。
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關(guān)鍵詞:
Abstract: 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℃. -
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