Magnetic regenerator material economizing method for 4K Gifford-McMahon cryocoolers using bakelite rod.

Magnetic regenerator materials, such as HoCu2, Er3Ni, Gd2O2S, and so on, are always needed to produce the cooling power at the temperature of 4.2 K using regenerative cryocoolers. The use of a large quantity of magnetic regenerator materials affects directly the fabrication cost of 4K cryocoolers. From this point of view, we introduce a magnetic regenerator material economizing method in this paper. An innovative regenerator structure was adopted for two-stage Gifford-McMahon (GM) cryocooler. The structure has a bakelite rod inserted in the co-axial layout of the 2nd stage regenerator in which HoCu2 spheres are filled. The cold temperature side of the 2nd stage regenerator is occupied with 50% by volume of the bakelite rod and HoCu2 spheres, and the warm side is packed with lead (Pb) spheres as a single layer. The bakelite rod is a dummy volume. Two types of conventional GM cryocoolers with power consumption of 1.3 and 7.3 kW, respectively, are tested. The experimental results show that the filling volume of HoCu2 spheres of 1.3 and 7.3 kW models is able to economize by 20% and 10% without deterioration of the cooling power at 4.2 K, respectively. In this paper, the regenerator structure and detailed experimental results will be presented. [ABSTRACT FROM AUTHOR]