Regensburg 2025 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 8: Measurement Technology and Cryogenics
TT 8.7: Talk
Monday, March 17, 2025, 16:45–17:00, H32
Experimental investigations of a frequency optimized Pulse Tube Cryocooler cooldown — •Jack Schmidt1,2, Bernd Schmidt1,2, and Andre Schirmeisen1,2 — 1Justus-Liebig-Universität Gießen — 2TransMIT GmbH
Working in research often requires lower temperatures to achieve material effects such as superconductivity. This is achieved by using cryogenic liquids or closed cycle cryocoolers. Later have sub genres of working principle and provide different positive and negative aspects. We focus on the usage of Gifford-McMahon-type pulse tube cryocoolers which provide temperatures down to 2.2 K with the usage of Helium. The cooling power at 4.2 K scales up to 5 Watts nowadays with an electrical input power of the compressor around 25 kW. [1] As for mechanical stability the cryostats often become bulky and heavy. Including temperature isolation of the cold parts the cooldown times become very large. As the cryocoolers are mostly optimized for ongoing low temperature operation the cooling process lacks adaptations for an ideal cooldown. Other findings on this topic suggest to adjust valves and frequency. [2] Here we present our findings on the cooling process of a cryocooler to reduce cooldown time while adjusting the frequency. We were able to reduce the cooling time of the cryocooler by 9 % , applying electrical heat the cooldown is reduced by 10 %.
[1] X. Hao et al., Development of a 5 W/4.2 K two-stage pulse tube cryocooler. CEC/ICMC, C2Or3A-03 (2023);
[2] R. Snodgrass et al., Nat. Commun. 15, 3386 (2024).
Keywords: PTC; Cryocooler; Pulsetube; Helium; Cooldown