Flight model performance test results of a helium dewar for the soft X-ray spectrometer onboard ASTRO-H

Yoshida, Seiji; Miyaoka, Mikio; Kanao, Kenichi; Tsunematsu, Shoji; Otsuka, Kiyomi; Hoshika, Shunji; Mitsuda, Kazuhisa; Yamasaki, Noriko Y.; Takei, Yoh; Fujimoto, R.; Sato, Yoichi; DiPirro, Mike; Shirron, Peter

doi:10.1016/j.cryogenics.2015.10.012

Cited by 18 publications

(15 citation statements)

References 6 publications

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“…4(b) to ∼5162 g, the lifetime of the LHe with the beginning-of-life cryocooler performance was estimated at ∼4.7 years, which is ∼0.2 years longer than that predicted by Yoshida et al 7 before the launch. This is because the initial LHe amount was ∼6% larger than they assumed (33.6 L).…”

Section: He Lifetime Estimationmentioning

confidence: 89%

“…The heat load from the JFET amplifiers through the harness between the IVCS and the DA is also input to the IVCS. This varies with the IVCS temperature and becomes 0.21 mW when the IVCS is at 24.5 K. 7 We model these positive heat loads at the He tank, IVCS, and OVCS, as shown in Fig. 1 as red circles and summarized in Table 1.…”

Section: Modeling Heat Generations and Coolings By He And Cryocoolersmentioning

confidence: 99%

“…Other shields are also supported by blocks bonded to these straps. 7 Note that the amount of LHe was 35.6 L at the launch.…”

Section: Introductionmentioning

confidence: 99%

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Thermal analyses for initial operations of the soft x-ray spectrometer onboard the Hitomi satellite

Noda

Mitsuda

Okamoto

et al. 2017

J. Astron. Telesc. Instrum. Syst

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Abstract. The soft x-ray spectrometer (SXS) onboard the Hitomi satellite achieved a high-energy resolution of ∼4.9 eV at 6 keV with an x-ray microcalorimeter array cooled to 50 mK. The cooling system utilizes liquid helium, confined in zero gravity by means of a porous plug (PP) phase separator. For the PP to function, the helium temperature must be kept lower than the λ point of 2.17 K in orbit. To determine the maximum allowable helium temperature at launch, taking into account the uncertainties in both the final ground operations and initial operation in orbit, we constructed a thermal mathematical model of the SXS dewar and PP vent and carried out time-series thermal simulations. Based on the results, the maximum allowable helium temperature at launch was set at 1.7 K. We also conducted a transient thermal calculation using the actual temperatures at launch as initial conditions to determine flow and cooling rates in orbit. From this, the equilibrium helium mass flow rate was estimated to be ∼34 to 42 μg∕s, and the lifetime of the helium mode was predicted to be ∼3.9 to 4.7 years. This paper describes the thermal model and presents simulation results and comparisons with temperatures measured in the orbit. © 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 DOI.

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Section: He Lifetime Estimationmentioning

confidence: 89%

Section: Modeling Heat Generations and Coolings By He And Cryocoolersmentioning

confidence: 99%

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Thermal analyses for initial operations of the soft x-ray spectrometer onboard the Hitomi satellite

Noda

Mitsuda

Okamoto

et al. 2017

J. Astron. Telesc. Instrum. Syst

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“…With nominal cryocooler operation and without ADR operation, the measured heat load to the He tank was 0.62 mW, and the thermal calculation predicted 0.64 mW. 15 Discrepancies of the shield temperatures were 10% or less, and it was concluded that the dewar thermal performance was verified. The predicted heat load in orbit including the expected contribution from ADR cycling was 0.75 mW with the beginning-of-life performance of the cryocoolers, and 1.00 mW with the end-of-life performance of the cryocoolers.…”

Section: Performance Verification On Groundmentioning

confidence: 99%

“…Details are described elsewhere. [13][14][15] The requirements for the cooling chain from room temperature to the ADR heat sink were to provide a thermal bath below 1.3 K for the CSI with a lifetime over 3 years in the nominal case, and 9 months in a contingency case (failure of one cryocooler case). It was designed to satisfy these requirements utilizing ≥30 L LHe and minimizing a heat load on the helium tank (He tank) to <1 mW.…”

Section: Designmentioning

confidence: 99%

Performance of the helium dewar and the cryocoolers of the Hitomi soft x-ray spectrometer

Fujimoto

Takei

Mitsuda

et al. 2017

J. Astron. Telesc. Instrum. Syst.

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Abstract. The soft x-ray spectrometer (SXS) was a cryogenic high-resolution x-ray spectrometer onboard the Hitomi (ASTRO-H) satellite that achieved energy resolution of 5 eV at 6 keV, by operating the detector array at 50 mK using an adiabatic demagnetization refrigerator (ADR). The cooling chain from room temperature to the ADR heat sink was composed of two-stage Stirling cryocoolers, a 4 He Joule-Thomson cryocooler, and superfluid liquid helium and was installed in a dewar. It was designed to achieve a helium lifetime of more than 3 years with a minimum of 30 L. The satellite was launched on February 17, 2016, and the SXS worked perfectly in orbit, until March 26 when the satellite lost its function. It was demonstrated that the heat load on the helium tank was about 0.7 mW, which would have satisfied the lifetime requirement. This paper describes the design, results of ground performance tests, prelaunch operations, and initial operation and performance in orbit of the flight dewar and the cryocoolers. © 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 DOI.

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Development status of the mechanical cryocoolers for the Soft X-ray Spectrometer on board Astro-H

Sato¹,

Sawada²,

Shinozaki³

et al. 2014

Cryogenics

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Flight model performance test results of a helium dewar for the soft X-ray spectrometer onboard ASTRO-H

Cited by 18 publications

References 6 publications

Thermal analyses for initial operations of the soft x-ray spectrometer onboard the Hitomi satellite

Thermal analyses for initial operations of the soft x-ray spectrometer onboard the Hitomi satellite

Performance of the helium dewar and the cryocoolers of the Hitomi soft x-ray spectrometer

Development status of the mechanical cryocoolers for the Soft X-ray Spectrometer on board Astro-H

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