TY - JOUR
T1 - Porous plug phase separator and superfluid film flow suppression system for the soft x-ray spectrometer onboard Hitomi
AU - Ezoe, Yuichiro
AU - DiPirro, Michael
AU - Fujimoto, Ryuichi
AU - Ishikawa, Kumi
AU - Ishisaki, Yoshitaka
AU - Kanao, Kenichi
AU - Kimball, Mark
AU - Mitsuda, Kazuhisa
AU - Mitsuishi, Ikuyuki
AU - Murakami, Masahide
AU - Noda, Hirofumi
AU - Ohashi, Takaya
AU - Okamoto, Atsushi
AU - Satoh, Yohichi
AU - Sato, Kosuke
AU - Shirron, Peter
AU - Tsunematsu, Shoji
AU - Yamaguchi, Hiroya
AU - Yoshida, Seiji
N1 - Funding Information:
aTokyo Metropolitan University, Department of Physics, Hachioji, Tokyo, Japan bNational Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, Maryland, United States cKanazawa University, Institute of Science and Engineering, Faculty of Mathematics and Physics, Kakuma-machi, Kanazawa, Ishikawa, Japan dJapan Aerospace and Exploration Agency, Institute of Space and Astronautical Science, Sagamihara, Kanagawa, Japan eSumitomo Heavy Industries, Ltd., Niihama, Ehime, Japan fNagoya University, Department of Physics, Chikusa-ku, Nagoya, Japan gUniversity of Tsukuba, Department of Engineering Mechanics and Energy, Tsukuba, Ibaraki, Japan hTohoku University, Frontier Research Institute for Interdisciplinary Sciences, Aoba, Sendai, Japan iJapan Aerospace Exploration Agency, Research and Development Directorate, Tsukuba, Ibaraki, Japan jTokyo University of Science, Department of Physics, Tokyo, Japan
Publisher Copyright:
© The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - When using superfluid helium in low-gravity environments, porous plug phase separators are commonly used to vent boil-off gas while confining the bulk liquid to the tank. Invariably, there is a flow of superfluid film from the perimeter of the porous plug down the vent line. For the soft x-ray spectrometer onboard ASTRO-H (Hitomi), its approximately 30-liter helium supply has a lifetime requirement of more than 3 years. A nominal vent rate is estimated as ∼30 μg/s, equivalent to ∼0.7 mW heat load. It is, therefore, critical to suppress any film flow whose evaporation would not provide direct cooling of the remaining liquid helium. That is, the porous plug vent system must be designed to both minimize film flow and to ensure maximum extraction of latent heat from the film. The design goal for Hitomi is to reduce the film flow losses to <2 μg/s, corresponding to a loss of cooling capacity of <40 μW. The design adopts the same general design as implemented for Astro-E and E2, using a vent system composed of a porous plug, combined with an orifice, a heat exchanger, and knife-edge devices. Design, on-ground testing results, and in-orbit performance are described.
AB - When using superfluid helium in low-gravity environments, porous plug phase separators are commonly used to vent boil-off gas while confining the bulk liquid to the tank. Invariably, there is a flow of superfluid film from the perimeter of the porous plug down the vent line. For the soft x-ray spectrometer onboard ASTRO-H (Hitomi), its approximately 30-liter helium supply has a lifetime requirement of more than 3 years. A nominal vent rate is estimated as ∼30 μg/s, equivalent to ∼0.7 mW heat load. It is, therefore, critical to suppress any film flow whose evaporation would not provide direct cooling of the remaining liquid helium. That is, the porous plug vent system must be designed to both minimize film flow and to ensure maximum extraction of latent heat from the film. The design goal for Hitomi is to reduce the film flow losses to <2 μg/s, corresponding to a loss of cooling capacity of <40 μW. The design adopts the same general design as implemented for Astro-E and E2, using a vent system composed of a porous plug, combined with an orifice, a heat exchanger, and knife-edge devices. Design, on-ground testing results, and in-orbit performance are described.
KW - ASTRO-H (Hitomi)
KW - cryogenics
KW - film flow
KW - porous plug
KW - soft x-ray spectrometer
KW - superfluid helium
KW - x-ray microcalorimeter
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U2 - 10.1117/1.JATIS.4.1.011203
DO - 10.1117/1.JATIS.4.1.011203
M3 - Article
AN - SCOPUS:85032992607
SN - 2329-4124
VL - 4
JO - Journal of Astronomical Telescopes, Instruments, and Systems
JF - Journal of Astronomical Telescopes, Instruments, and Systems
IS - 1
M1 - 011203
ER -