Mechanical design of a 3-stage ADR for the Astro-H mission

► The design of the 3-stage ADR ensures structural survival at cryogenic launch temperature. ► The design of the 3-stage ADR limits thermal shorting that would hinder performance. ► Mechanical properties of two of the main structural materials were discovered at warm temperature. ► Mechanical properties of two of the main structural materials were discovered at cryogenic temperature. ► The ADR will be vibe tested at cryogenic temperature to further validate the design. The X-ray micro-calorimeter array in the Soft X-ray Spectrometer (SXS) instrument on Astro-H will be cooled by a 3-stage adiabatic demagnetization refrigerator (ADR). The ADR consists of two mechanically independent assemblies. When integrated with a mounting structure and the detector assembly, they form a self-contained unit that will be inserted into the top end of a liquid helium tank. The unique configuration requires many components and sub-assemblies to be thermally isolated from their structural mount. Normally in an ADR this is limited to suspending cold salt pills within their (much warmer) magnets, but in the case of SXS, it also involves one ADR stage being supported by, but thermally isolated from, the helium tank. This paper will describe the complex thermal and mechanical design of the SXS ADR, and summarize vibration and mechanical properties tests that have been performed to validate the design.