Electron tube cathode
 A metal layer of not more than 2.0 .mu.m thick is formed on a base, containing nickel as the main ingredient and a reducing agent such as silicon and magnesium, by depositing tungsten by an electron beam under heating in a vacuum. The base is heat treated in a hydrogen atmosphere at 800.degree. to 1,100.degree. C. An emissive material layer, containing an alkali earth metal oxide and 0.01 to 25 wt % of a rare earth metal oxide, the alkali earth metal oxide containing at least barium oxide, is formed on the metal layer. Thus, life characteristics of the cathode, especially during the operation at a high current density such as not less than 2A/cm.sub.2, are greatly enhanced. 
Mitsubishi Denki Kabushiki Kaisha
H H
H01J H01J
inventional inventional
Masato Keiji Toyokazu Keiji Takashi Kinjiro Takuya Ryo Hisao
Saito Fukuyama Kamata Watanabe Shinjou Sano Ohira Suzuki Nakanishi