Development of mechanical cryocoolers for Astro-H/SXS

• Published in: Cryogenics (Guildford) 2010-09, Vol.50 (9), p.500-506
• Main Authors: Sato, Yoichi, Sugita, Hiroyuki, Mitsuda, Kazuhisa, Nakagawa, Takao, Fujimoto, Ryuichi, Murakami, Masahide, Otsuka, Kiyomi, Tsunematsu, Shoji, Kanao, Kenichi, Narasaki, Katsuhiro
• Format: Article
• Language: English
• Subjects: Adiabatic flow; Applied sciences; Arrays; B. 3He; Coolers; Cooling; Cryogenics; E. Joule–Thomson coolers; E. Stirling; Energy; Energy. Thermal use of fuels; Exact sciences and technology; F. Space cryogenics; Liquid helium; Refrigerating engineering; Refrigerating engineering. Cryogenics. Food conservation; Refrigerators; Spectrometers; Techniques. Materials; X-rays
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/j.cryogenics.2010.02.003

The Soft X-ray Spectrometer (SXS) is a high-resolution spectrometer with an X-ray micro-calorimeter array onboard the Japanese X-ray astronomy satellite Astro-H, planned for launch in 2013. The micro-calorimeter is operated at cryogenic temperature of 50 mK provided by the Adiabatic Demagnetization Refrigerator (ADR) with a heat sink of 1.3 K liquid helium stored in the SXS Dewar. To extend the liquid helium lifetime to over 3 years in orbit, two types of mechanical cryocoolers are installed: 20 K-class double-staged Stirling (2ST) coolers and a 1 K-class Joule–Thomson (JT) cooler. Improvement of mechanical cryocoolers has been investigated and verified for higher reliability and cooling performance. The engineering model (EM) of upgraded mechanical cryocoolers was fabricated for a long lifetime test. The required cooling power of 200 mW at 20 K for the 2ST cooler and 10 mW at 1.7 K for the JT cooler are achieved by EM test.