Note on the design of simple indium O-ring seals

Abstract

Various different applications of indium O-ring seals are briefly reviewed. A critical factor in the construction of any indium pressure-type seal is the finish of the surface cold welding to the indium. We present the results of some tests on surface finishes achieved by machining and grinding, which indicate certain conditions which ensure the integrity of the seal. Specifically, we find that if the metal surface has to be ground, it should be ground, and then polished to a surface granularity of less than 5 μ. This condition can be obtained using a grinding powder with a mesh size of 3200 or greater. Alternatively, careful surface preparation using a lathe furnishes an equally satisfactory finish, provided no attempt is made to ‘‘improve’’ the surface using emery paper, etc. In the latter case, the fine helical pattern imparted by the lathe is essential for the fabrication of a reliable seal.

A hydrogen leak-tight, transparent cryogenic sample container for ultracold-neutron transmission measurements

“…The term "glass" here is meant in a broader sense to refer to optically transparent materials and includes quartz, vitreous silica, sapphire, and similar materials. The main advances in the field of metalto-glass joints that are hydrogen and helium-tight, have been made in the 1950s-1960s [21][22][23][24][25] , among others to seal a large liquid hydrogen bubble chamber 26 , and in the 1980s [27][28][29][30] . A substantial overview of published indium seal designs was given by Turkington and Harris-Lowe 28 .…”

“…The main advances in the field of metalto-glass joints that are hydrogen and helium-tight, have been made in the 1950s-1960s [21][22][23][24][25] , among others to seal a large liquid hydrogen bubble chamber 26 , and in the 1980s [27][28][29][30] . A substantial overview of published indium seal designs was given by Turkington and Harris-Lowe 28 . All previous designs that describe metal-to-glass joints use, however, flat glass slabs of appreciable thicknessin the range of several millimeters to centimeters -and of corresponding mechanical strength.…”

“…The scattering of thermal and cold neutrons from cryogenic liquids and solids is a well established experimental technique. Most of the time, sample containers and their neutron beam windows are machined from aluminum alloy, because of its favorable post-irradiation behavior (short half-life of 2.5 min of the 28 Al isotope, which is created by 27 Al capturing a neutron), low neutron scattering and absorption cross section, and easy workability. Thermal and cold neutrons have wavelengths of 1 to 10 Ångström and are therefore practically insensitive to the aluminum's neutron-optical potential, material inhomogeneities and surface roughness.…”

Anti-reflection coated vacuum window for the Primordial Inflation Polarization ExploreR (PIPER) balloon-borne instrument

“…A review of design considerations for indium O-ring seals can be found in Turkington and Harris-Lowe. 46 The key steps in the window assembly and installation procedure used here are summarized in Fig. 7.…”

Anti-reflection Coated Vacuum Window for the Primordial Inflation Polarization ExploreR (PIPER) balloon-borne instrument

“…More recently, Döge and Hingerl 45 described the use of a hydrogen-tight cryogenic vacuum seal employing indium wire gaskets for amorphous silica windows. A review of design considerations for indium O-ring seals can be found in Turkington and Harris-Lowe 46 .…”