Development of SHI 1.0 W 4 K Two‐stage Pulse Tube Cryocoolers

Sumitomo Heavy Industries, Ltd. (SHI) has been developing 4 K pulse tube cryocoolers for cooling MRI Magnet Systems, Small Superconducting Magnets, SQUIDs, X‐ray detectors, etc. Since 2002, a joint team at SHI‐Tanashi and SHI‐APD Cryogenics has been developing high efficiency, high cooling capacity and high reliability 4 K pulse tube cryocoolers. Much effort has been expended to improve cooling capacity, reliability, and temperature stability. A typical cooling capacity of 1.2 W @ 4.19 K at the second stage and 50 W @ 44.8 K at the first stage has been achieved with 7.2 kW compressor input power. The pulse tube reliability and temperature stability have been improved by improvements in the valve design, and the system reliability has been improved by developing a new fail safe compressor.