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New approach to enhanced heat exchange efficiencies at ultralow temperatures

Research output: Contribution to Journal/MagazineComment/debatepeer-review

<mark>Journal publication date</mark>1/06/1986
<mark>Journal</mark>Physical review B
Issue number11
Number of pages3
Pages (from-to)7803-7805
Publication StatusPublished
<mark>Original language</mark>English


We examine the heat transfer between a sintered metallic powder and liquid 3He at ultralow temperatures. With the combination of a renormalization-group approach with the Lanczos method, a microscopic model is analyzed to yield the low-frequency density of states ρ(ω) of the sinter. In the weak-coupling limit ρ(ω) possesses a pronounced low-frequency peak leading to an enhanced heat transfer coefficient at low temperatures. This enhancement is shown to occur when the ratio of the long-wavelength velocity of sound Cs in the sinter to its velocity Cb in the bulk metal is small and can be optimized by minimizing this ratio.