| 摘要 |
PURPOSE: To provide such as electron tube with an oxide cathode as being capable of maintaining stable electron emission property with high current density for a long time. CONSTITUTION: An oxide cathode has a cap substrate metal 14 containing mainly nickel(Ni) and a very small amount of reducing metal such as magnesium(Mg), silicon(Si) and zirconium(Zr) and an electron emission material layer 15 formed of metal oxide containing barium(Ba), strontium(Sr) or calcium(Ca) and provided on the substrate metal 14. In an electron tube with the oxide cathode, the electron emission material layer 15 is mixed by 0.2-3.0wt.% content of aluminum oxide(Al2 O3 ) powder 16 of average size 0.5-20μm. With the mixture of the aluminum oxide(Al2 O3 ) powder 16, the electric resistance of the electron emission material layer 15 at a high temperature is reduced to show stable electron emission property with high current density for a long time. |
