| 摘要 |
PURPOSE:To suppress exhaustion of Ba in high current density operation by covering a base with a layer containing chiefly oxidated alkali earth metal incl. at least barium and also oxidated rare earth metal in specific wt.%, and thereover forming a BaO layer. CONSTITUTION:A base 1 consisting of Ni as main component is covered with an electron emitting substance layer 2 containing chiefly oxidated alkali earth metal 11 incl. at least barium and also oxidated rare earth metal 12 in 10-50wt.%, and over this mixture layer 2 a BaO layer 13 of 200nm thick or less is formed. This enables sufficient conduction of dissociation of the oxidated rare earth metal 12 in the electron emitting substance layer 2 and solid solution phenomenon of the rare earth metal in the Ni base 1. Thereby the amount of Ba supply to the surface of cathode is increased, Ba evaporation suppressed, and high current density operation over 4A/cm<2> made practicable. |
