Beam window devices and methods of making same

Abstract

A beam tube having a hole or 'window' covered by a thin, beam permeable membrane is provided with a polymeric ring for minimizing stress concentration in the membrane adjacent the periphery of the hole to relieve stress concentrations that would otherwise occur when the membrane is forced inwardly into the hole by atmospheric or other pressure on the exterior of the tube. The exterior surface of the housing for the beam tube contains means for retaining the polymeric ring in a predetermined location on the exterior surface. The retaining means which retain the polymeric material away from the hole may comprise an annular channel formed in the exterior surface of the front wall, an annular raised inner ridge formed on the exterior surface, an annular raised outer ridge also formed on the exterior surface to define an annular track between the outer and inner ridges, or a ring of flow preventing material on the exterior surface of the housing. In a manufacturing method, a liquid polymer precursor is placed on the exterior surface of the front wall and retained by the retaining means when the membrane, precursor and housing are heated to an elevated bonding temperature so as to cure the polymer precursor to form the polymeric ring retained by the retaining means away from the hole during the bonding step.