| Abstract: | A sealed, passively pumped, polycrystalline ceramic vacuum chamber and method for fabricating the chamber are disclosed. The body of the vacuum chamber is made from a polycrystalline ceramic, for example, alumina. The vacuum chamber includes one or more windows made from a transparent ceramic, for example, sapphire, to accommodate optical access, while remaining amorphous-glass free to minimize or eliminate helium permeation. The vacuum chamber components are joined via laser welding or furnace brazing and the completed chamber is bakeable at temperatures up to 400° C. The vacuum chamber can operate at high or ultra-high vacuum pressures for an extended period through the use of one or more getter-based pumps. The vacuum chamber may include one or more atomic sources depending upon the application. |