Apparatus with a cap and cover assembly, an electron gun with a cap assembly, and a method of using a tube

摘要

A cap can comprise an aperture, and an attenuator may block the aperture during at least one point in time. In one embodiment, the attenuator can include a cover that may be displaced by a spring. In another embodiment, such as an electron gun, may comprise a support cap with an aperture, a displaceable cover that may cover the aperture, and a spring. A material attached to the spring and acting as a fuse may release the spring and expose the aperture after an electrical current blows the "fuse". In yet another embodiment, a method for using a tube may comprise evacuating the tube while a cover covers an aperture in the support cap of a electron gun that is at least partially in the tube and moving the cover to expose the aperture after the tube is sealed.