| 摘要 |
PROBLEM TO BE SOLVED: To provide a cathode for an electron tube which can stably operate under high electric current density. SOLUTION: In a cathode for an electron tube, the cathode for an electron tube is formed by forming a metallic layer 4 mainly composed of metal of at least one or more kinds among tungsten, molybdenum and tantalum and an electron emitting substance layer 5 containing an oxide 6 of alkaline earth metal containing at least barium on it and an oxide 7 of rare earth metal of 0.01 to 25wt.% on a substrate 1 whose main component is composed of nickel and which contains silicon or magnesium as a reducing agent. Though this cathode is operated under electric current density of at least 2A/cm<2> , a service life characteristic is remarkably improved more than a conventional one. |
