Double Stage Helium Sorption Coolers

Abstract

We have developed two double stage helium sorption coolers. The first unit comprises a ³He stage coupled to a ⁴He stage. This cooler can be operated from any cold heat sink with adequate cooling power (typically ≥0.5 W) at less than 5 K, and provides temperature down to 260 mK. It is a self contained cooler with no moving parts, which can be simply thermally attached to a cold heat sink. Its operation is controlled by two heaters. The second unit is a double stage ³He cooler with the same features. It requires for its operation a cold heat sink at a temperature below 3 K, and provides temperatures down to 204 mK. Both double stage coolers are currently being experimentally characterized, and preliminary results are presented.