Published in Cryogenics: Reducing the hydrogen content in liquid helium


Contamination of liquid helium with hydrogen, even at the low levels of 10s of ppm, can lead to blockage of helium intake capillaries needed to operate 1K pots for experiments below 4K, e.g. 3He and dilution refrigerators, thus bringing such experiments to halt. This has presented a severe challenge in many laboratories. Here, we introduce a hydrogen content measurement sensor in our in-house helium liquefaction plant, and present three measures which have eliminated all blockages of capillaries for more than two years. D. Sifrig et al. Cryogenics 114, 103239 (2021)