Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 9 No. 2 June 1999|
（School of Materials Science and Engineering,BeijingPolytechnic University, Beijing100022, P. R. China）
Abstract:Lanthanum-containing cathodes are an attractive alternative to thorium tungsten cathodes because of their low work function and their comparatively low operating temperatures. A La-Mo carbonized cathode was described, which had a high thermionic emission; it was made up in a similar way to the Th-Wcathode, but possesses high emission values. The thermionic tube equipped with La-Mo carbonized cathode was designed for comparison with Th-W cathode tube. It was experimentally verified that La-Mo cathode has higher thermionic emission effectiveness and its operating temperature is about 200℃lower than that of Th-Wcathode. The emission current density of La-Mo wire satisfies for electron tubes as Th-W filament. Astable emission current has been obtained with La-Mo carbonized cathode tubes for more than 1 800 h. From the results it is clear that the emission stability of La-Mo cathode satisfies the requirements for the replacement of Th-W filament.
Key words: cathode rare-earth molybdenum thermionic emission La2O3