Thermionic Electron Emission Stability of Mo-La2O3 Cathode
来源期刊：JOURNAL OF RARE EARTHS2004年第3期
论文作者：周美玲 张久兴 万小峰 左铁镛 刘燕琴 周文元
Key words：Mo-La2O3 cathode; electron emission stability; carbonizing; lifetime; rare earths;
Abstract: The carbonizing process and its influence on the thermionic electron emission properties of Mo-La2O3 cathode materials were investigated. The carbonized temperature, carbonized time and the pressure of C6H6 are key factors of the carbonizing process. The carbonized ratio of Mo-La2O3 cathode increases with the increase of carbonizing temperature at low temperature. The highest carbonized ratio is 19.7% obtained at 1723 K, then the carbonized ratio decreases rapidly if temperature increases further. The carbonized ratio increases with the prolongation of carbonizing time during the process of first 6 min., after that the carbonization ratio changes little with the time increase, and the carbonized ratio increases with the increase of the C6H6 pressure when the pressure is low, the maximum carbonized ratio reaches 19.7% at 1.5×10-2 Pa, then the carbonized ratio goes down sharply when the C6H6 pressure is over 1.5×10-2 Pa. The emission properties at different operated temperatures and the emission current stability of FU-6051 tubes equipped with Mo-La2O3 cathodes were also studied in the article. The study results indicate that the emission can keep stable only when the operating temperature is from 1700 to 1800 K and the carbonized layer must be composed by Mo2C only. The FU-6051 tubes equipped with Mo-La2O3 cathodes have excellent stable emission current and the lifetime exceeds 3000 h when the cathode′s carbonized ratio is 19.7% operated at 1773 K.
周美玲1，张久兴1，万小峰1，左铁镛1，刘燕琴1，周文元1
(1.The key Laboratory of Advanced Functional Materials, Ministry of Education, Beijing University of Technology, Beijing 100022, China)
Abstract:The carbonizing process and its influence on the thermionic electron emission properties of Mo-La2O3 cathode materials were investigated. The carbonized temperature, carbonized time and the pressure of C6H6 are key factors of the carbonizing process. The carbonized ratio of Mo-La2O3 cathode increases with the increase of carbonizing temperature at low temperature. The highest carbonized ratio is 19.7% obtained at 1723 K, then the carbonized ratio decreases rapidly if temperature increases further. The carbonized ratio increases with the prolongation of carbonizing time during the process of first 6 min., after that the carbonization ratio changes little with the time increase, and the carbonized ratio increases with the increase of the C6H6 pressure when the pressure is low, the maximum carbonized ratio reaches 19.7% at 1.5×10-2 Pa, then the carbonized ratio goes down sharply when the C6H6 pressure is over 1.5×10-2 Pa. The emission properties at different operated temperatures and the emission current stability of FU-6051 tubes equipped with Mo-La2O3 cathodes were also studied in the article. The study results indicate that the emission can keep stable only when the operating temperature is from 1700 to 1800 K and the carbonized layer must be composed by Mo2C only. The FU-6051 tubes equipped with Mo-La2O3 cathodes have excellent stable emission current and the lifetime exceeds 3000 h when the cathode′s carbonized ratio is 19.7% operated at 1773 K.
Key words:Mo-La2O3 cathode; electron emission stability; carbonizing; lifetime; rare earths;
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