Development of a 5 W at 80 K Stirling-Type Pulse Tube Cryocooler

Abstract

Stirling-type pulse tube coolers (PTCs) promise higher reliability, lower mechanical vibrations, and lower manufacturing costs, as compared to conventional Stirling cold fingers. We report the state of development of pulse tube cold fingers that were designed for operation on an existing linear Stirling compressor (Leybold Polar SC 7). Two lab models, a U-shaped and an inline PTC, were designed, fabricated and optimized at Giessen University. So far, the U-shaped PTC has reached a minimum no-load temperature of 32.4 K, and cooling powers of 3 W at 60 K and 6 W at 80 K are available at an electrical input power of 200 W to the compressor. The inline version achieves an even higher cooling capacity of 8.1 W at 80 K with 200 W of input power. On the basis of the U-shaped cold head, Leybold has fabricated three engineering samples, which were then tested for reproducibility. In view of a compact cold head for practical applications, also the effect of buffer volume size on the cooling performance was investigated. The cooling capacities of all engineering models were found to be reproducible in the range 5.3 W ± 0.3 W at 80 K with 200 W of input power.