HE-4 REFRIGERATOR FOR SPACE

A compact, self-contained He-4 refrigerator suitable for use in space has been developed. The refrigerator is recyclable, has no moving part s, and requires only electrical connections for heaters and thermomete rs to operate from a T less-than-or-equal-to 4.2 K cold stage. It cons ists of a sorption pump filled with charcoal and an evaporator filled with lightweight silicose sponge to contain the liquid He-4 in zero-gr avity. Gas-gap heat switches attached to the pump and to the evaporato r allow the refrigerator to be cycled in any orientation and to be ope rated in zero-gravity. The refrigerator has an operating temperature o f 1.10 K and a cooling capacity of 6.5J when operated from a 4.2 K col d stage, and an operating temperature of 0.96K and a cooling capacity of 13J when operated from a 2 K cold stage. The refrigerator has been vibration tested and has been successfully used in a sounding rocket e xperiment.