| 摘要 |
PURPOSE:To prevent thermal vaporization of Ba from the periphery and improve reliability by defining depth of fused layer formed at the side surface of sintered body of porous tungsten to which electron radiation substance is impregnated to a specified deapth. CONSTITUTION:The hole cavity portions of disk type porous tungsten sintered body 32 is impregnated with electron radiation substance 33. At the time of formation to the specified size by the laser processing, after impregnation of this electron radiation substance 33, the periphery is fused eliminating the hole cavity portionthe fused layer 6 consisting of column type crystal is formed at the surface other than the electron radiation substance surface A, particularly to the side surface. The depth d of fushed layer 36 is preset to 20-100mum. Thereby, vaporization of electron radiation substance, particularly Ba which is thermally vaporized during operation of electron tube can be lowered. Moreover, leak between electrodes can be prevented and reliability can be enhanced. |
