| 摘要 |
In a vacuum tube with a window through which radiation is passed, an entrance window member is formed of radiation transparent metal, such as titanium or a titanium-base alloy. An entrance window supporting frame, which defines the window, is formed of iron or an alloy containing iron. The flat inner surface of the entrance window member is tacked to the flat outer surface of the entrance window supporting frame along the whole perimeter thereof by tack welding. An intermediate member formed of a metal containing gold or silver is interposed between the respective peripheral edge portions of the entrance window member and the entrance window supporting frame, whereby the entrance window member is finally welded to the peripheral edge portion of the entrance window supporting frame along the whole perimeter thereof in a vacuum-tight manner by continuous spot welding. The position for the final welding is at a predetermined distance from the weld zone of the tack welding. The tack welding permits continuous spot welding with use of the intermediate member without variations of welding conditions in the weld zone. |
