| 摘要 |
PROBLEM TO BE SOLVED: To provide an electronic tube with a cathode which can stably operate under a high current density. SOLUTION: On a base body 1 whose main component is made of nickel, a metal layer 4 whose main component is at least one kind or more of metal out of tungsten, molybdenum, tantalum, and thereon an electron emission substance layer 5 which contains an alkali earth metal oxide 6 containing at least barium, and rare earth metal oxide 7 which is a rare earth metal oxide of 0.01 to 0.25 percent by weight and contains at lest one of scandium oxide, yttrium oxide are formed so as to form a cathode for an electronic tube, although the cathode is operated at least at a current density of 2A/cm<2> , life characteristics are significantly improved. |
