Regenerator for Vuilleumier heat pump

In a Vuilleumier heat pump including fluid chambers interconnected by a conduit in which a regenerator is mounted, the conduit conducting fluid from one chamber to another and longitudinally through the regenerator so that heat is exchanged between the fluid and the regenerator, the improvement wherein the regenerator comprises a body having an internal surface contacted by the fluid flowing longitudinally through the regenerator for guiding the fluid flow, a porous heat absorbing/emitting structure housed within the body, and a flow interrupting structure provided laterally between the heat absorbing/emitting structure and the internal surface for inhibiting the leakage of fluid between the heat absorbing/emitting structure and the internal surface, wherein the flow interrupting structure comprises circumferential grooves formed in the internal surface, and ring devices mounted in respective ones of the grooves, an inner periphery of each ring device projecting laterally inwardly beyond the inner surface and contacting the porous heat absorbing/emitting structure to cause the fluid to flow laterally inwardly along the ring devices and into the porous heat absorbing/emitting structure.