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Thermoacoustic analysis of 3 K thermal buffer tubes and implications for miniaturization of 1 Hz pulse tube refrigerators
Published
Author(s)
Ryan Snodgrass, Joel Ullom
Abstract
The performance of pulse tube refrigerators is inextricably tied to the effectiveness of thermal buffer tubes, yet this component is rarely studied or analyzed in detail. In this work, we use thermoacoustic analysis to explain fundamental characteristics of 3 K to 300 K buffer tubes with and without Gedeon streaming. Our analysis is aimed towards the low-frequency, Gifford-McMahon-type (GM-type) pulse tube refrigerators that routinely reach extremely low temperatures, but which may be more susceptible to buffer tube losses due to relatively large boundary layers. Simplified expressions show that---in the absence of Gedeon streaming---buffer tube losses are too large to allow cooling power near 3 K. It is possible that the double-inlet configuration has been so critical for these very low temperatures because it enables Gedeon streaming, which is a very effective way to absorb buffer tube losses using the cooling power of the regenerator. As low-frequency pulse tube refrigerators operating near 3 K are miniaturized, a progressively larger proportion of this regenerator cooling capacity must be used to absorb losses from the progressively less-adiabatic buffer tube. Numerical tools suggest that the smallest state-of-the-art commercial coolers are already nearing miniaturization limits.
Proceedings Title
Cryocoolers 24
Citation
<i>Cryocoolers 24</i> (International Cryocooler Conference 24, Syracuse, NY, US, 15-JUN-26 to 18-JUN-26)
Snodgrass, R.
and Ullom, J.
(2026),
Thermoacoustic analysis of 3 K thermal buffer tubes and implications for miniaturization of 1 Hz pulse tube refrigerators, Cryocoolers 24, Syracuse, NY, US, [online], https://nps-ext.nist.gov/nps/nps_public_api/api/Publication/file/962513 (Accessed October 30, 2026)