A high-efficiency coaxial pulse tube cryocooler with 500 W cooling capacity at 80 K

•A coaxial pulse tube cryocooler was developed.•It can offer 520 W of cooling power at cooling temperature of 80 K.•With cooling power of 285 W at 80 K, the relative Carnot efficiency is 20.9%.

High-temperature superconductivity power-grid technologies require a highly reliable and efficient cryocooler with cooling power of 100 W to kilowatt level at liquid-nitrogen temperatures to produce cryogenic environments. This paper describes the design of a coaxial Stirling-type pulse tube cryocooler to meet this need. In the designed cryocooler, the regenerator and pulse tube are lengthened to avoid possible temperature inhomogeneity. In an experiment, the azimuthal temperature difference at the middle of the regenerator was less than 30 K. With 7.6 kW electric power input, the cryocooler offers more than 520 W cooling power at 80 K corresponding to a relative Carnot efficiency of 18.2%. When the cooling power was less than 370 W, the efficiency is higher than 20%.