| 摘要 |
PURPOSE:To retain the long life at high current density by forming a thermoionic emission substance layer with a substance mainly comprising alkaline earth metal oxide including barium and containing scandium oxide and alkaline earth metal silicate. CONSTITUTION:A thermoionic emission layer 2a formed on a substrate 1 made of nickel containing a trace of reducing element is formed with a substance mainly comprising alkaline earth metal oxide including barium and containing 0.1-20 wt% scandium oxide and 0.01-0.5 wt% alkaline earth metal silicate. This offers the long life at 2-4 times higher current density compared with the conventional cathode, and an electron tube cathode having low cost, less restriction on production, and high reliability can be obtained. |
