Measurement of the thermal accommodation coefficient of helium on a crystalline silicon surface at low-temperatures
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arXiv
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| Auteurs principaux: | , , , , , , , |
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| Format: | Preprint |
| Publié: |
2024
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| _version_ | 1866913237109309440 |
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| author | Franke, Alexander Sültmann, Nils Reinhardt, Christoph Croatto, Sandy Schaffran, Jörn Masalehdan, Hossein Lindner, Axel Schnabel, Roman |
| author_facet | Franke, Alexander Sültmann, Nils Reinhardt, Christoph Croatto, Sandy Schaffran, Jörn Masalehdan, Hossein Lindner, Axel Schnabel, Roman |
| contents | Next-generation gravitational wave observatories are expected to use cryogenically cooled, pendulum-suspended 200 kg test mass mirrors from a crystalline material such as crystalline silicon. During operation of the observatories, these mirrors undergo heating due to the absorption of laser radiation of up to a watt. Low noise cooling techniques need to be developed. Low-pressure helium exchange gas at 5 K might contribute to the challenging task. Here, we report the measurement of the helium accommodation coefficient $α(11\,\mathrm{K}<T< 30\,\mathrm{K})$, which is the probability that a helium atom thermalises with a surface at a given temperature, when reflected from it. We find $α(T) > 0.7$ for temperatures < 20 K, which increases the cooling power compared to recently used assumptions. The idea of free molecular flow helium gas cooling is thus supported and might find application in some observatory concepts. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2402_11977 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Measurement of the thermal accommodation coefficient of helium on a crystalline silicon surface at low-temperatures Franke, Alexander Sültmann, Nils Reinhardt, Christoph Croatto, Sandy Schaffran, Jörn Masalehdan, Hossein Lindner, Axel Schnabel, Roman Instrumentation and Detectors Next-generation gravitational wave observatories are expected to use cryogenically cooled, pendulum-suspended 200 kg test mass mirrors from a crystalline material such as crystalline silicon. During operation of the observatories, these mirrors undergo heating due to the absorption of laser radiation of up to a watt. Low noise cooling techniques need to be developed. Low-pressure helium exchange gas at 5 K might contribute to the challenging task. Here, we report the measurement of the helium accommodation coefficient $α(11\,\mathrm{K}<T< 30\,\mathrm{K})$, which is the probability that a helium atom thermalises with a surface at a given temperature, when reflected from it. We find $α(T) > 0.7$ for temperatures < 20 K, which increases the cooling power compared to recently used assumptions. The idea of free molecular flow helium gas cooling is thus supported and might find application in some observatory concepts. |
| title | Measurement of the thermal accommodation coefficient of helium on a crystalline silicon surface at low-temperatures |
| topic | Instrumentation and Detectors |
| url | https://arxiv.org/abs/2402.11977 |