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Proceedings Paper

Thermal analyses for initial operations of the Soft X-Ray Spectrometer (SXS) onboard ASTRO-H
Author(s): Hirofumi Noda; Kazuhisa Mitsuda; Atsushi Okamoto; Yuichiro Ezoe; Kumi Ishikawa; Ryuichi Fujimoto; Noriko Yamasaki; Yoh Takei; Takaya Ohashi; Yoshitaka Ishisaki; Ikuyuki Mitsuishi; Seiji Yoshida; Michael DiPirro; Peter Shirron
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Paper Abstract

The Soft X-ray Spectrometer (SXS) onboard ASTRO-H (Hitomi) achieved a high energy resolution of ~ 4.9 eV at 6 keV with an X-ray microcalorimeter array kept at 50 mK in the orbit. The cooling system utilizes liquid helium, and a porous plug phase separator is utilized to confine it. Therefore, it is required to keep the helium temperature always lower than the λ point of 2.17 K in the orbit. To clarify the maximum allowable helium temperature at the launch also considering the uncertainties of the initial operation in the orbit, we constructed a thermal mathematical model of the SXS dewar which properly implements the helium mass flow rate through the porous plug, and carried out time-series thermal simulations. Based on the results, the maximum allowable helium temperature at the launch was set at 1.7 K. We also conducted a transient thermal calculation using the actual temperatures at the launch as initial conditions. As a result, the helium mass flow rate when the helium temperature was in equilibrium is estimated to be 34–42 μg/s, and the life time of the helium mode is predicted to be ~ 3.9–4.7 years. The present paper reports model structures, simulation results, and the comparisons with temperatures measured in the orbit.

Paper Details

Date Published: 18 July 2016
PDF: 9 pages
Proc. SPIE 9905, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray, 99053R (18 July 2016); doi: 10.1117/12.2231356
Show Author Affiliations
Hirofumi Noda, Tohoku Univ. (Japan)
Kazuhisa Mitsuda, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan)
Atsushi Okamoto, Japan Aerospace Exploration Agency (Japan)
Yuichiro Ezoe, Tokyo Metropolitan Univ. (Japan)
Kumi Ishikawa, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan)
Ryuichi Fujimoto, Kanazawa Univ. (Japan)
Noriko Yamasaki, Institute of SInstitute of Space and Astronautical Science, Japan Aeropace and Astronautical Science (Japan)
Yoh Takei, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan)
Takaya Ohashi, Tokyo Metropolitan Univ. (Japan)
Yoshitaka Ishisaki, Tokyo Metropolitan Univ. (Japan)
Ikuyuki Mitsuishi, Nagoya Univ. (Japan)
Seiji Yoshida, Sumitomo Heavy Industries, Ltd. (Japan)
Michael DiPirro, NASA Goddard Space Flight Ctr. (United States)
Peter Shirron, NASA Goddard Space Flight Ctr. (United States)


Published in SPIE Proceedings Vol. 9905:
Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray
Jan-Willem A. den Herder; Tadayuki Takahashi; Marshall Bautz, Editor(s)

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