The flexure-bearing technology of Thales Cryogenics BV is being used in an extensive range of pulse-tube and Stirling cryocoolers. Compressors based on this flexure-bearing technology have a high reliability, long lifetime, and low vibrations. They are therefore the compressors of choice for high-end cryocoolers. Recently, the range of compressors has been extended with a larger compressor, capable of delivering more than 300 W of mechanical power. Apart from the abovementioned characteristics, this particular compressor model has a high efficiency of more than 85 % at its rated performance. In this paper, the design validation of this compressor is presented. This includes the verification of the individual loss mechanisms present in linear motor driven compressors. Furthermore, the potential of this compressor is demonstrated by its application in two cryocoolers. First the performance of a large, 15 W pulse tube (LPT9710) is presented. The combination of the large compressor with a newly designed pulse tube has resulted in a cooler with an efficiency of up to 15 % of Carnot. Finally, measurements on a combination of the large compressor with a 20 mm Stirling cold finger are presented to demonstrate the potential performance of a – yet to be developed – large-capacity Stirling cold finger.
D. Willems, J. Mullié, W. v.d. Groep, T. Benschop
THALES Cryogenics BV Eindhoven, The Netherlands