Development of Helium-3 Compressors and Integration Test of Closed-Cycle Dilution Refrigerator System

Abstract

The closed-cycle dilution refrigerator for space application is an ongoing development to improve the performance of the open-cycle dilution refrigerator successfully used on the Planck mission. The use of the closed-cycle refrigerator is considered in various projects in X-ray and far-infrared space instruments for astrophysics (ATHENA, SPICA) and in advanced studies for future CMB polarization surveys (LiteBIRD). We have shown that for sub-Kelvin applications, this refrigerator is fully competitive with some ADR-based solutions. The helium-3 circulator is a key component to achieve the closed-cycle dilution refrigerator. JAXA and SHI have developed such a compressor by adapting the compressor of the space qualified 1K-class Joule-Thomson cooler. A coupled test of this compressor in combination with the dilution refrigerator developed by CNRS, Air Liquide and the CNES has been performed and successfully achived to cool down from 18 K to 70 mK. In this paper, details of the target, design and circulation performance of the compressor system are shown. The results of first integration and first cooling measurement are also described.