Cooling Performance of a Small GM Cryocooler with a New Ceramic Magnetic Regenerator Material

Abstract

A new ceramic magnetic regenerator material Gd₂O₂S (GOS) has been developed for use in regenerative cryocoolers in the 4 K region. Experimental results of the cooling performance of a small Gifford-McMahon cycle (GM) cryocooler with GOS are described in this paper. A small GM cryocooler with 0.l W-class cooling capacity at 4.2 K was used in the experiments. The cryocooler has been developed for low-T_c superconducting device cooling or test sample cooling for physical property measurements, etc. The cryocooler is driven by single phase 100V electricity and the power consumption is about 1.2 kW (50 Hz). The conventional second-stage regenerator of the cryocooler is composed of lead spheres and HoCu₂ spheres. In our experiments, a part of HoCu₂ was replaced with a new ceramic magnetic regenerator material GOS and the cooling capacity was measured. The second-stage cooling capacity at 4.2 K was improved by more than 20% by replacing a part of the HoCu₂ with GOS.