Reducing the hydrogen content in liquid helium

Sifrig, Dominik and Martin, Sascha and Zumbühl, Dominik M. and Schönenberger, Christian and Marot, Laurent. (2021) Reducing the hydrogen content in liquid helium. Cryogenics, 114. p. 103239.

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Official URL: https://edoc.unibas.ch/86344/

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Helium has the lowest boiling point of any element in nature at normal atmospheric pressure. Therefore, any unwanted substance like impurities present in liquid helium will be frozen and will be in solid form. Even if these solid impurities can be easily eliminated by filtering, liquid helium may contain a non negligible quantity of molecular hydrogen. These traces of molecular hydrogen are the causes of a known problem worldwide: the blocking of fine capillary tubes used as flow resistors in helium evaporation cryostats to achieve temperatures below 4.2 K. This problem seriously affects a wide range of cryogenic equipment used in low temperature physics research and leads to a dramatic loss of time and costs due to the high price of helium. Here, we present first the measurement of molecular hydrogen content in helium gas. Three measures to decrease this molecular hydrogen are afterward proposed; (i)improving the helium quality, (ii) release of helium gas in the atmosphere during purge time for the regeneration cycle of the helium liquefierâEurotms internal purifier, and (iii) installation of two catalytic converters in a closed helium circuit. These actions have eliminated all blockages of capillaries at low temperatures now for more than two years.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Experimentalphysik Nanoelektronik (Schönenberger)
UniBasel Contributors:Schönenberger, Christian and Zumbühl, Dominik M and Marot, Laurent and Sifrig, Dominik and Martin, Sascha
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:07 Apr 2022 14:40
Deposited On:07 Apr 2022 14:04

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