| 摘要 |
PURPOSE:To obtain a cathode to which a monoatomic layer with a low work function can be easily supplied by using a heat-resistant porous base plate impregnated with an electron-emitting material and forming a thin layer composed of a metallic material with a high melting point and Sc and/or Sc oxide on the electron-emitting surface of the porous base plate. CONSTITUTION:A cathode pellet 1 is composed of a porous W base 2 with a porosity of 20-25% and a hole 3. The porous base 2 is made of either an element such as Mo, Ir, Pt or Re or one of their alloys. The hole 3 is impregnated with an electron-emitting material. It is preferable that the thickness of a thin layer 8 be 10nm-1mum. The thin layer 8 contains a metallic material with a high melting point which is composed of at least one metal element selected from among W, Mo, Ir, Os, Re and Pt. It is preferable that the amount of each of Sc and/or Sc2O3 be about 1-20wt%. The thin layer 8 is formed by vacuum sputtering, baking a powder of the original material or attaching a sintered body. |
