Abstract
Stirling coolers using refrigerants, such as helium, take effect on the environment problem arising on a terrestrial scale. The authors developed the Stirling cooler for the ultra-low temperature region used with the equipment for vacuum, biomedical and so on. It has the cooling capacity of 45W at 77K. This paper describes performance test results of the Stirling cooler on operating temperatures and working gas mean pressures, and introduces an ultra-low temperature freezer operating at 93K in which the Stirling cooler is installed.
