Rencent Development of G-M Cryocooler

The G-M cryocooler, also known as the Gifford-McMahon cycle cryocooler, has been invented for more than half a century. It is based on the principle of adiabatic gas expansion and continuous Simon expansion refrigeration through valve gas supply. Its working process mainly includes four steps: isochoric pressure rise, isobaric expansion, isochoric pressure drop, and isobaric compression, to finally achieve the refrigeration effect. Compared with other refrigeration equipment, G-M cryocoolers are simple in structure, easy to operate, highly reliable and have a long service life. These features make them widely used in the fields of cryogenic physics, cryogenic medicine, high temperature superconductivity, semiconductors and industrial gases, etc. To meet the growing demand in high-temperature superconductivity, cryogenic physics, and other fields, ultra-low temperature G-M cryocoolers with light weight and large-cooling capacity are continuously making technical progress. These cryocoolers are not only more compact in design and higher in efficiency, but also perform excellently in various cryogenic applications, meeting the diverse needs of scientific research and industrial applications. In order to provide a reference for relevant researchers to optimize and develop G-M cryocoolers, this paper reviews the latest development of G-M cryocoolers at liquid helium, liquid hydrogen and liquid nitrogen temperatures based on the optimization of regenerator materials and regenerator structures that affect the performance of G-M cryocoolers. This work mainly focuses on how to improve the performance and efficiency of G-M cryocoolers at different cryogenic temperatures by improving the regenerator design and material selection. By optimising the secondary regenerator and displacer stroke lengths, the cooling capacity of the cryocooler in the vertical direction has been improved and the performance degradation in horizontal operation has been reduced. These research results not only promote the development of G-M cryocooler technology, but also provide technical support for a wider range of cryogenic applications in the future.