Abstract: A heat-stationed bayonet connector suitable for connecting liquid cryogen sources and refrigeration loads to a cryogenic fluid transfer line or for connecting components such as flexible sections, etc., into the transfer line. The incorporation of a cold heat station in the bayonet connector and its thermal connection to a coolant makes it possible to intercept heat flow along the length of the bayonet and thereby to minimize heat losses associated with the connector. The use of a cryogenic coolant transfer line in the form of a flexible bypass connecting the male and female sections of the bayonet makes it possible to use the bayonet connector in a transfer line which incorporates a cooled radiation shield along essentially its entire length.

Abstract: A helium transfer line adapted to be constructed in extended lengths and to carry liquid helium and/or 4.2.degree.K helium gas with minimum loss of refrigeration capacity due to heat leaks into and through the line. The transfer line, in its basic structure, comprises a fluid helium process line, radiation shielding, vacuum jacketing and a cryogenic coolant line in thermal contact with the radiation shielding and carrying a cryogenic coolant such as liquid nitrogen. Line components, comprising heat-stationed bayonets with or without LN.sub.2 bypass lines, expansion/contraction joints, and flexible sections and, if desired, valves, ell-sections and tee-sections, are designed to be integrated into the basic structure so that this structure may be carried through essentially the entire length of the line.