Investigation of the 2nd stage regenerator materials of a Gifford-McMahon cryocooler

Gifford-McMahon冷凍機の2段目蓄冷材の検討

Investigation of the 2nd stage regenerator materials of a Gifford-McMahon cryocooler

Creators Fukuda Yusuke

Creators Tamura Kota

Creators Masuyama shinji

The purpose of this study is improving the cooling power at 4.2 K of a two-stage Gifford-McMahon (G-M) cryocooler. We take notice of a specific heat of the 2nd stage regenerator materials. The experiments have been conducted from two ways. Firstly, the lead (Pb), HoCu2 and Gd2O2S (GOS) spheres were used as the 2nd stage regenerator materials. The sphere diameter of Pb, HoCu2 and GOS are 0.4, 0.2 and 0.25 mm, respectively. Their materials were filled in the 2nd stage regenerator as a three-layer structure. Secondly, the Pb spheres were replaced to the stainless steel (SUS) screens (200 mesh) or empty space (Emp). A conventional two-stage G-M cryocooler with an air cooled compressor of 1.3 kW at 60 Hz has been tested. The operating frequency of the G-M cryocooler is 1.2 Hz. From a experimental results, the cooling power of 0.22 W achieved when the volumetric ratio was Pb:HoCu2:GOS = 40:35:25 %.Next, the Pb spheres were replaced to the SUS screens or Emp. The
cooling power were 0.12 W (SUS:HoCu2 = 20:80) and 0.14 W (Emp: HoCu2 = 20:80) at 4.2 K. The empty space brought the higher cooling power than the stainless steel screens.

[ISSN]0387-9232

[NCID]AN00031668