| 摘要 |
PURPOSE:To improve thermionic emission capability by adding a certain amount of rare earth metal oxide into an electron emission substance covering a linear shaped cathode body with its main constituent being tungsten. CONSTITUTION:In an oxide cathode comprising a linear shaped cathode body mainly containing tungsten with its surface covered with an electron emitting layer, the electron emitting layer contains mainly alkaline earth metal oxide containing at least barium and being added with 0.1-20wt.% of rare earth metal oxide. For example, to a ternary carbonate of alkaline earth metals of Ba, Sr, and Ca is added fine powder of scandium oxide as an oxide of rare earth metal and applied to cover the surface of the fine tungsten wire by electrodeposition to form a directly heated oxide cathode. This provides an oxide cathode of a high thermionic emission capability, long life, and less deterioration in the thermionic emission efficiency. |
