Vibration isolation system for cryocoolers of Soft X-ray Spectrometer (SXS) onboard ASTRO-H (Hitomi)

Soft X-ray Spectrometer (SXS) onboard ASTRO-H (named Hitomi after launch) is a microcalorimeter-type spectrometer, installed in a dewar to be cooled at 50 mK. The energy resolution of the SXS engineering model suffered from micro-vibration from cryocoolers mounted on the dewar. This is mitigated for the flight model by introducing vibration isolation systems between the cryocoolers and the dewar. The detector performance of the flight model was verified before launch of the spacecraft in both ambient condition and thermal-vac condition, showing no detectable degradation in energy resolution. The in-orbit performance was also consistent with that on ground, indicating that the cryocoolers were not damaged by launch environment. The design and performance of the vibration isolation system along with the mechanism of how the micro-vibration could degrade the cryogenic detector is shown.

[1]  Ryuichi Fujimoto,et al.  The Astro-H high resolution soft x-ray spectrometer , 2016, Astronomical Telescopes + Instrumentation.

[2]  Ryuichi Fujimoto,et al.  In-orbit operation of the ASTRO-H SXS , 2016, Astronomical Telescopes + Instrumentation.

[3]  Ryuichi Fujimoto,et al.  Flight model performance test results of a helium dewar for the soft X-ray spectrometer onboard ASTRO-H , 2016 .

[4]  Regis P. Brekosky,et al.  The design, implementation, and performance of the Atro-H SXS calorimeter array and anti-coincidence detector , 2016, Astronomical Telescopes + Instrumentation.

[5]  Ryuichi Fujimoto,et al.  Performance of the helium dewar and cryocoolers of ASTRO-H SXS , 2016, Astronomical Telescopes + Instrumentation.

[6]  Ryuichi Fujimoto,et al.  Development status of the mechanical cryocoolers for the Soft X-ray Spectrometer on board Astro-H , 2014 .

[7]  Tomomi Watanabe,et al.  System design and implementation of the detector assembly of the Astro-H soft x-ray spectrometer , 2018 .

[8]  Hideyuki Mori,et al.  ASTRO-H Soft X-ray Telescope (SXT) , 2011, Astronomical Telescopes and Instrumentation.

[9]  Naoko Iwata,et al.  Thermal Control System of X-ray Astronomy Satellite ASTRO-H: Current Development Status and Prospects , 2014 .

[10]  Ryuichi Fujimoto,et al.  In-flight performance of the Soft X-ray Spectrometer detector system on Astro-H , 2016, Astronomical Telescopes + Instrumentation.

[11]  Yoshiharu Namba,et al.  The ASTRO-H X-ray astronomy satellite , 2014, Astronomical Telescopes and Instrumentation.