Low helium permeability atomic frequency standard cell and method for forming same

摘要

An atomic frequency standard cell having low helium permeability includes first and second windows sealed by fusible annular gaskets to sealing surfaces defined by a tubular cylindrical body. One of the windows defines an opening, and a fill tube is sealed the window adjacent the opening by a tube gasket. The gaskets are made of a lower softening point glass such as borosilicate glass, and the body, windows and fill tube are formed of a higher softening point glass such as aluminosilicate glass. The assembly is sealed together by heating it to a temperature that causes the gaskets to fuse and seal the adjacent components together.