| 摘要 |
PURPOSE:To make an initial electron emitting property stable and preferable all the times so as to suppress its deterioration during a lifetime by incorporating one or more kinds of specific metals into an alkaline earth metallic oxide layer. CONSTITUTION:In a cathode sleeve 1 with a heater 4 housed therein, an alkaline earth metallic oxide layer 3 is formed on a nickel substrate 2 thereof. Sc and one or more kinds of Pt, Ir and Rh are incorporated into the layer 3. Sc is added as a composite salt of scandium oxide and barium oxide (for example, Ba2Sc4O9). The content of Pt, Ir and Rh is 1ppm-5wt.% in total. |
