Abstract: A vuilleumier-cycle refrigeration system of the type including first and second communicating, sealed, cylindrical, vessels having first and second displacers respectively mounted therein in sliding, sealing contact with the inner walls thereof, includes magnetic linkage between the two displacers for driving the displacers within the sealed vessels without contaminating the sealed vessels. With regard to the magnetic linkage, there are smaller, auxiliary cylindrical vessels coupled respectively to the first and second vessels, having smaller diameters, and thinner walls than the first and second vessels. Rods attached to the displacers and extending into the auxiliary vessels have magnetic material followers attached thereto. Magnetic-material drivers are moveable along the auxiliary vessels, opposite the followers, to thereby attract and move the magnetic-material followers and their attached displacers.This is a division of application Ser. No. 665,848, filed Mar. 17, 1976, now U.S. Pat. No. 4,118,943.

Abstract: A vuilleumier-cycle refrigeration system of the type including first and second communicating, sealed, cylindrical, vessels having first and second displacers respectively mounted therein in sliding, sealing contact with the inner walls thereof, includes magnetic linkage between the two displacers for driving the displacers within the sealed vessels without contaminating the sealed vessels. With regard to the magnetic linkage, there are smaller, auxiliary cylindrical vessels coupled respectively to the first and second vessels, having smaller diameters, and thinner walls than the first and second vessels. Rods attached to the displacers and extending into the auxiliary vessels have magnetic material followers attached thereto. Magnetic-material drivers are moveable along the auxiliary vessels, opposite the followers, to thereby attract and move the magnetic-material followers and their attached displacers.

Abstract: Refrigeration systems of the type including first and second communicating, sealed, cylindrical, vessels having respective first and second piston-like elements reciprocating axially therein are characterized by having the vessels positioned in a line along a single axis and having a rod or shaft extending along the axis through a sliding seal for connecting the piston-like elements. A coupling for connecting the rod with one of the piston-like elements allows "lost" axial motion of the rod, without a corresponding motion of the attached piston, over a first portion of the range of axial travel of the rod in both directions. An intercommunicating line is also included for intercommunicating appropriate ends of the elongated vessels.Such refrigeration systems can operate in various modes of operation, such as stirling-cycle modes of operation, and Vuilleumier-cycle modes of operation.

Abstract: An elongated cryogenic envelope is comprised of a plurality of sections each including an outer tube and a coaxial inner tube spaced therefrom by a support means. The outer tubes of each section are joined together to form a continuous outer tube. The inner tubes, however, are unjoined so that fluid can flow therebetween, but an expansion means is affixed to at least one of the inner tubes to separate the vacuum chamber from the fluid passing through the space between the inner tubes.

Abstract: Refrigeration systems of the type including first and second communicating, sealed, cylindrical, vessels having respective first and second piston-like elements reciprocating axially therein are characterized by having the vessels positioned in a line along a single axis and having a rod or shaft extending along the axis through a sliding seal for connecting the piston-like elements. A coupling for connecting the rod with one of the piston-like elements allows "lost" axial motion of the rod, without a corresponding motion of the attached piston, over a first portion of the range of axial travel of the rod in both directions. An intercommunicating line is also included for intercommunicating appropriate ends of the elongated vessels.Such refrigeration systems can operate in various modes of operation, such as stirling-cycle modes of operation, and Vuilleumier-cycle modes of operation.

Abstract: A superconducting power transmission line is comprised of sections of rigid cryogenic envelope and sections of flexible cryogenic envelope. The rigid sections are comprised of rigid inner and outer tubes having a refrigeration shield located in a vacuum chamber therebetween. The flexible sections are comprised of flexible inner and outer tubes surrounded by reinforcing braid. The rigid and flexible inner and outer tubes are joined together and a refrigeration tube which is in contact with the rigid section's shield is coiled about the inner flexible tube.

Abstract: An elongated cryogenic envelope includes a support-spacer for locating a plurality of refrigeration tubes at selected radial and circumferential locations within a vacuum chamber formed between inner and outer coaxial tubes. The support-spacer includes a high-thermal-conductivity ring surrounding the inner tube and a plurality of hollow epoxy-fiberglass, titanium-tipped spokes extending between the outer tube and the high-thermal-conductivity ring surrounding the inner tube.

Abstract: An elongated cryogenic envelope including an outer tube and an inner tube coaxially spaced within said inner tube so that the space therebetween forms a vacuum chamber for holding a vacuum. The inner and outer tubes are provided with means for expanding or contracting during thermal changes. A shield is located in the vacuum chamber intermediate the inner and outer tubes; and, a refrigeration tube for directing refrigeration to the shield is coiled about at least a portion of the inner tube within the vacuum chamber to permit the refrigeration tube to expand or contract along its length during thermal changes within said vacuum chamber.

Abstract: A plurality of cryogenic envelope sections are joined together to form a power transmission line. Each of the sections is comprised of inner and outer tubes having multilayer metalized plastic spirally wrapped within a vacuum chamber formed between the inner and outer tubes. A refrigeration tube traverses the vacuum chamber, but exits one section and enters another through thermal standoffs for reducing heat-leak from the outer tube to the refrigeration tube. The refrigeration tube passes through a spirally wrapped shield within each section's vacuum chamber in a manner so that the refrigeration tube is in close thermal contact with the shield, but is nevertheless slideable with respect thereto.

Abstract: A dewar vessel adapted to have fluid pumped therefrom to reduce its internal pressure and temperature has a porous plate located in the path of the pumped fluid. For a given fluid pressure and viscosity, the pores are sized to provide a sufficiently low pressure drop across the plate while still providing a sufficiently large surface area for the transfer of heat between the vessel and the pumped fluid. A sheet-like liquid-retaining collar extends from the interior wall of the dewar container toward the center thereof so that the container liquid is restrained from moving along the container's inner wall when the container is tilted.

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.