Design and predicted performance of the 3-stage ADR for the Soft-X-ray Spectrometer instrument on Astro-H

• Published in: Cryogenics (Guildford) Vol. 52; no. 4-6; pp. 165 - 171
• Main Authors: Shirron, Peter J., Kimball, Mark O., James, Bryan L., Wegel, Donald C., Martinez, Raul M., Faulkner, Richard L., Neubauer, Larry, Sansebastian, Marcelino
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier Ltd 01.04.2012; Elsevier
• Subjects: Adiabatic demagnetization refrigerator; Applied sciences; Arrays; Astronomy; Cryogenics; Detectors; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Helium; Liquid helium; Magnetic refrigeration; Missions; Refrigerating engineering; Refrigerating engineering. Cryogenics. Food conservation; Refrigerators; Soft x-rays; Space cryogenics; Spectrometers; Techniques. Materials; Magnetic refrigeration; Space cryogenics; Adiabatic demagnetization refrigerator; Astronomy; Adiabatic demagnetization; Superfluid; Refrigerator; X ray; Lifetime; Cryogenics; Liquid helium; Silicon; Refrigeration; Heat sink
• ISSN: 0011-2275; 1879-2235
• DOI: 10.1016/j.cryogenics.2012.01.019

► The 3-stage ADR for the Soft X-ray Spectrometer to be flown on Astro-H has been designed to work with two different heat sinks. ► These include a 1.3K superfluid helium tank and a 4.5K Joule–Thomson cooler. ► The engineering model ADR has been built and performance tested. ► The predicted hold time of the ADR with liquid helium present is 90h. The Japanese Astro-H mission will include the Soft X-ray Spectrometer (SXS) instrument provided by NASA/GSFC. The SXS will perform imaging spectroscopy in the soft X-ray band using a 6×6 array of silicon microcalorimeters operated at 50mK. The detectors will be cooled by a 3-stage adiabatic demagnetization refrigerator (ADR). The configuration allows the ADR to operate with both a 1.3K superfluid helium bath and a 4.5K cryocooler as its heat sink. Initially, when liquid helium is present, the two coldest stages of the ADR will operate in a single-shot mode to cool the detectors from 1.3K. During this phase of the mission, the 3rd stage may be used to reduce the net heat load on the liquid helium and extend its lifetime. When the liquid is depleted, the 2nd and 3rd stages will operate in a continuous mode to maintain the helium tank at about 1.3K, allowing continued operation of the 1st stage (in a single-shot mode) and hence the SXS instrument. This paper describes the design and operating modes of the ADR, as well as details of critical components.