| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a cathode having high current density of an electron beam by forming an electron emitting substance layer mainly composed of alkaline earth metal oxide or the base metal mainly composed of nickel, and laying/ forming/heating rare earth metal or a rare earth metal compound on the surface of the electron emitting substance layer. SOLUTION: An electron emitting substance layer 12 is laid/formed on the upper surface of the base metal 11 by supporting the base metal 11 by a cathode support stand. An electron beam control grid 14 forming an electron beam passing hole is formed in front of the electron emitting substance layer 12 so that a heater 13 to heat a base board is arranged on the inside surface of the base metal 11. Here, the base metal 11 contains a small quantity of magnesium and silicon by being mainly composed of nickel, and the electron emitting substance layer 12 is desirably composed of oxide of alkaline earth metal such as Ba, Sr and Ca. A rare earth metal compound 15 is laid/formed on the surface of the electron emitting substance layer 12. Therefore, an electron having high electric current density is emitted from a cathode for an electron tube.</p> |
