Abstract: An improved Vuilleumier cycle refrigerator is disclosed. To reduce fluid contamination and inactive refrigerant volume, the hot and cold fluid displacers of the refrigerator are driven by a magnetic drive mechanism. The magnetic drive mechanism has a first and second assembly. The first assembly is contained in the fluid chamber together with the hot and cold displacers; the second assembly including the drive motor is mounted exteriorly of the fluid chamber. The first and second assemblies of the drive mechanism include adjacent magnets separated by the wall of the fluid chamber. Thus, the first and second assemblies are coupled together by their magnetic field for rotation to drive the hot and cold displacers and the fluid chamber provides an hermetic seal to contain the working fluid thereby removing the motor with its air space and contaminants from the fluid chamber.