In-orbit selection of cryocooler drive frequencies for XRISM/Resolve

Gary A. Sneiderman; Meng P. Chiao; Caroline A. Kilbourne; F. Scott Porter; Masahiro Tsujimoto

doi:10.1117/12.3020590

21 August 2024 In-orbit selection of cryocooler drive frequencies for XRISM/Resolve

Gary A. Sneiderman, Meng P. Chiao, Caroline A. Kilbourne, F. Scott Porter, Masahiro Tsujimoto

Proceedings Volume 13093, Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray; 1309369 (2024) https://doi.org/10.1117/12.3020590
Event: SPIE Astronomical Telescopes + Instrumentation, 2024, Yokohama, Japan

Conference Poster

Abstract

The XRISM/Resolve instrument cooling system uses adiabatic demagnetization refrigerators (ADRs) to cool the detectors to 50 mK and Joule-Thomson and Stirling cryocoolers to reduce heat load on the He tank supporting the ADRs. Resolve was designed with tunable cryocooler drive frequencies so that interference could be avoided. The cryocooler generated micro-vibration changes with drive frequency and that micro-vibration causes interference and degrades instrument performance. Poor drive frequency choices have been shown to dramatically impact ADR cooling power, temperature stability, detector noise, and degrading spectroscopic performance. However, some choices are free of these features, allowing the instrument to satisfy its performance requirements with significant margin. Thus, the choice of drive frequencies is critical to achieving peak instrument performance. The drive frequencies of the Joule- Thomson cooler, near 52 Hz, and the Stirling coolers, near 15 Hz, were adjusted in three scan sequences while measuring interference to narrow candidate frequency options. Choices were based on stability of the 50 mK control thermometer, changes in the ADR demagnetization rate, and changes in detector noise. These scans were performed routinely during ground testing. Surprisingly though, the results were not repeatable after the Dewar was warmed and recooled but were repeatable when remeasured during the same test campaign. Since the good/bad drive frequencies change during Dewar warmup/cooldown, and possibly after vibration events, the drive frequencies could not be finalized before launch. This paper describes the cryocooler frequency scan measurements and compares the results during instrument commissioning to those performed during ground tests.

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Gary A. Sneiderman, Meng P. Chiao, Caroline A. Kilbourne, F. Scott Porter, and Masahiro Tsujimoto "In-orbit selection of cryocooler drive frequencies for XRISM/Resolve", Proc. SPIE 13093, Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 1309369 (21 August 2024); https://doi.org/10.1117/12.3020590

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