With the stringent requirement from the user community for high-resolution multichannel detectors which cause much heat generation, a future space-borne infrared radiometer on an Earth observation satellite must incorporate a small closed cycle refrigerator instead of the passive radiator which has been used for rejecting heat from small size detectors of satellite radiometers in the past. The Vuilleumier cooler, one such refrigerator, is a heat engine which uses heat energy rather than mechanical energy to cyclically pressurize the working gas. This machine has the potential advantages of long lifetime and low mechanical vibration. This paper first describes the specifications required for the machine, and next the details of design and the test results. As typical specification values, the machine has cooling capacity of 1.5 watts at 80K under input heater power of 150W, charged working gas pressure of 2.5MPa and cycle speed of 4s-1. The limitation of total weight is 6kg. The performance of the machine has been mapped including off-design points. The results show that 1.6 watts was obtained, that the nominal cooling capacity was obtained under the input heater power of 146W, and that 2.2W was the maximum cooling capability. The efficiency as a figure of merit value defined as input power/cooling capacity at 80K was about 135 for cooling capacity of 1W, and 80 for cooling capacity of 2W. It can be concluded that the small Vuilleumier cooler satisfied the preliminary specifications imposed at the beginning.
