| 摘要 |
<p>PROBLEM TO BE SOLVED: To maintain the radiating characteristic and the lifetime characteristic at a level equal to a general impregnated cathode, and while to reduce the power consumption by specifying diameter of a pellet, which is impregnated with the electron emitting material, in relation to the thickness of the pellet, and forming outer diameter of a lower end of an outside sleeve larger than the outer diameter of an upper end thereof. SOLUTION: An inside sleeve 10 is formed into a cylindrical shape, of which one end is closed and formed with a recessed part 12, and a bottom surface of a pellet 30 is installed in this recessed part 12 by laser welding. An outside sleeve 20 is formed so that diameter of a lower end 24 thereof is formed larger than diameter of an upper end thereof 22. With this structure, a power saving impregnated cathode can be provided without changing design of an existing cathode support 8, and heat loss to the outside can be reduced. Diameter D of the pellet 30 is reduced, and thickness H is increased. Diameter D of the pellet 30 is set at 1.5 times or less in relation to the thickness H. Desirably, heater current is set at 340mA or less in the condition that heater voltage (cathode temperature = 990 deg.C) is set at about 6.3 V.</p> |
