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Etude et réalisation d'une ADR spatiale 4 K - 50 mK

Abstract : Highly sensitive detectors required for astrophysics missions demand temperatures of about 50 mK to operate with the targeted sensitivity. This PhD work is dedicated on the research and development of Adiabatic Demagnetization Refrigerators (ADR) for space in the 4 K - 50 mK range. In particular, this cryocooler is required to be efficient with optimized mass.The key points of this work are the development of a method allowing the identification of highly efficient paramagnetic materials and the improvement of thermal heat switches. Among the material studied, YbGG (Yb3Ga5O12) was identified to have a great potential as a magnetic refrigerant in the 1.5 K - 0.4 K range, which was confirmed by its characterization. Transient thermal short circuits may appear on the gas-gap thermal switches under the working conditions of this cryocooler. This study allowed us to suppress or to considerably attenuate this effect. Finally, a cryocooler prototype consisting of 3 ADR stages was designed and built.
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Submitted on : Friday, January 19, 2018 - 5:09:07 PM
Last modification on : Wednesday, October 14, 2020 - 3:46:36 AM
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  • HAL Id : tel-01688809, version 1



Diego Augusto Paixao Brasiliano. Etude et réalisation d'une ADR spatiale 4 K - 50 mK. Instrumentation et méthodes pour l'astrophysique [astro-ph.IM]. Université Grenoble Alpes, 2017. Français. ⟨NNT : 2017GREAY028⟩. ⟨tel-01688809⟩



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