Porous plug phase separator and superfluid film flow suppression system for the soft x-ray spectrometer onboard Hitomi

Yuichiro Ezoe; Michael DiPirro; Ryuichi Fujimoto; Kumi Ishikawa; Yoshitaka Ishisaki; Kenichi Kanao; Mark O. Kimball; Kazuhisa Mitsuda; Ikuyuki Mitsuishi; Masahide Murakami; Hirofumi Noda; Takaya Ohashi; Atsushi Okamoto; Yohichi Satoh; Kosuke Sato; Peter Shirron; Shoji Tsunematsu; Hiroya Yamaguchi; Seiji Yoshida

doi:10.1117/1.JATIS.4.1.011203

27 October 2017 Porous plug phase separator and superfluid film flow suppression system for the soft x-ray spectrometer onboard Hitomi

Yuichiro Ezoe, Michael DiPirro, Ryuichi Fujimoto, Kumi Ishikawa, Yoshitaka Ishisaki, Kenichi Kanao, Mark O. Kimball, Kazuhisa Mitsuda, Ikuyuki Mitsuishi, Masahide Murakami, Hirofumi Noda, Takaya Ohashi, Atsushi Okamoto, Yohichi Satoh, Kosuke Sato, Peter Shirron, Shoji Tsunematsu, Hiroya Yamaguchi, Seiji Yoshida

Author Affiliations +

Journal of Astronomical Telescopes, Instruments, and Systems, Vol. 4, Issue 1, 011203 (October 2017). https://doi.org/10.1117/1.JATIS.4.1.011203

Abstract

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.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Yuichiro Ezoe, Michael DiPirro, Ryuichi Fujimoto, Kumi Ishikawa, Yoshitaka Ishisaki, Kenichi Kanao, Mark O. Kimball, Kazuhisa Mitsuda, Ikuyuki Mitsuishi, Masahide Murakami, Hirofumi Noda, Takaya Ohashi, Atsushi Okamoto, Yohichi Satoh, Kosuke Sato, Peter Shirron, Shoji Tsunematsu, Hiroya Yamaguchi, and Seiji Yoshida "Porous plug phase separator and superfluid film flow suppression system for the soft x-ray spectrometer onboard Hitomi," Journal of Astronomical Telescopes, Instruments, and Systems 4(1), 011203 (27 October 2017). https://doi.org/10.1117/1.JATIS.4.1.011203

Received: 20 April 2017; Accepted: 3 October 2017; Published: 27 October 2017

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