Abstract: A multi-stage cryogenic refrigerator utilizing the Gifford-McMahon cycle has an external regenerator in each stage. The external regenerators are vertically stacked and connected in series, so that expanding gas is allowed to flow through the regenerators without significant obstruction or turning motion. The lower regenerators operate at progressively lower temperatures. The packing material within each regenerator has a higher specific heat than that of the regenerator immediately above as determined at the operating temperature of the regenerator.

Abstract: A cryogenic refrigerator utilizing the Gifford-McMahon cycle that includes a cylinder having a warm end and a cold end, a displacer slidably mounted within the cylinder to form an expansion chamber at the cold end of the cylinder, a regenerator housing having an inlet end connected to a source of refrigerant and an outlet end connected to said expansion chamber whereby refrigerant from said source is passed in and out of said chamber through the regenerator, and a heat exchanger for placing the warm end of the displacer cylinder in heat transfer relationship with the inlet end of the regenerator housing whereby heat energy from the warm end of the cylinder is transferred rapidly into the refrigerant as it moves out of the regenerator back to the source.

Abstract: A regenerator unit arranged for mounting in the flow circuit carrying a refrigerant (helium gas) between stages of a two-stage Gifford-McMahon cryorefrigerator. The unit is housed in a sleeve extending between the expansion chamber of the first stage and the low temperature heat exchanger. A locking mechanism both suspends and seals the regenerator within the sleeve so that the regenerator cannot move either axially or radially and refrigerant cannot bypass the unit. The locking mechanism makes assembling and disassembling the unit in the refrigerator readily simple.