A dual refrigerator assembly for cryogen-free superconducting magnet applications

Reliable refrigeration is critical to the viability of cryogen-free superconducting magnets. The servicing of a refrigerator coldhead must not interrupt the magnet operation. A dual refrigerator coldhead assembly is described in this paper which enables the disconnection of a coldhead for servicing while a second coldhead provides continuous cooling. The two-stage Balzers UCH-130 coldheads are thermally connected to the cryostat thermal shield at the first stage and to the superconducting magnet at the second stage. The assembly includes high-T/sub c/ superconducting current leads heat stationed between the first and second stages of the coldheads in order to minimize the heat leak to the magnet. Vibration isolation components minimize the transmission of the coldhead vibration to the magnet and the thermal shield. This paper describes the design, fabrication, and testing of the dual refrigerator assembly.< >