Commercial Cryocoolers for use in HTS Applications

The emerging commercial HTS applications place expectations of high reliability, long service intervals, and environmentally robust cryocoolers. Whilst there have been several attempts at developing cryocoolers in the 300W to 2000W (at 77K) for these applications, the market need has yet to be satisfied. Fabrum Solutions in collaboration with Absolut Systems have formed a joint venture company, AFCryo, that produces a commercially available range of acoustic pulse tube cryocoolers featuring low maintenance, high power output, and cost effective operation. These cryocoolers utilize diaphragm pressure wave generators that hermetically seal the working fluids of the compressor from the helium working gas, ensuring zero degradation of the pulse tube performance. The efficiency, low servicing, and cost effectiveness of these cryocoolers suit the demands of HTS applications, in turn making the commercial success of HTS devices more achievable

High Capacity Pulse Tube Cryocooler

International audienceHigh capacity pulse tube coolers are presently under development at CEA/SBT. The Development Models of the pulse tube cold finger feature an in-line configuration to ease manufacturing and optimisation of the sizing. A cooling power of 5.2 W at 80 K has been achieved with 200 W of total electrical power, 128 W PV work, and a rejection temperature of 298 K provided by water cooling. This work has been accomplished using a standard wearing linear compressor operating at a fixed frequency of 50 Hz and equipped with a laser transducer to measure the stroke. An ultimate temperature of 38 K has also been achieved. Based on these results, a pulse tube cold finger has been developed for cooling down of HTS filters banks for an UMTS RF base station demonstrator (SUPRACOM project). A standard wearing linear compressor from THALES Cryogenics with an adjustable frequency drive electronics has been used. A performance of 7.7 W at 80 K has been achieved with 200 W of total electrical power and with heat rejection at 298 K; the PV work is about 140 W. This last result is presently being used for the design of a coaxial shape pulse tube cooler. This cold finger will be ultimately supplied with a flexure bearing compressor to increase the reliability. The matching of the com-pressor and the cold head are discussed