This article describes the principal design features and performance test results of a threehyphen;stage Giffordndash;McMahon cycle cryogenic refrigerator by which the authors have achieved a nohyphen;load temperature of 3.3 K and succeeded in helium liquefaction. The refrigeration capacity was 20 mW at 4.2 K and the helium liquefaction rate was 10 cm3/h. The key point of the success is the selection of GdxEr1minus;xRh compounds as a regenerator material. This is the first time that a Giffordndash;McMahon refrigerator has liquefied helium without the use of a Joulendash;Thomson stage.
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