'Heat from above' heat capacity measurements in liquid 4He

Richard A.M. Lee, Andrew R. Chatto, Dmitri A. Sergatskov, Alex V. Babkin, Stephen T.P. Boyd, A. M. Churilov, T. D. McCarson, Talso C.P. Chui, P. K. Day, Robert V. Duncan, David L. Goodstein

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


We have made heat capacity measurements of superfluid 4He at temperatures very close to the lambda point, Tλ, in a constant heat flux, Q, when the helium sample is heated from above. In this configuration the helium enters a self-organized (SOC) heat transport state at a temperature TSOC(Q), which for Q ≥ 100 n W/cm2 lies below Tλ. At low Q we observe little or no deviation from the Q = 0 heat capacity up to TSOC(Q); beyond this temperature the heat capacity appears to be sharply depressed, deviating dramatically from its bulk behaviour. This marks the formation and propagation of a SOC/superfluid two phase state, which we confirm with a simple model. The excellent agreement between data and model serves as an independent confirmation of the existence of the SOC state. As Q is increased (up to 6 μ W/cm2) we observe a Q dependent depression in the heat capacity that occurs just below TSOC(Q), when the entire sample is still superfluid. This is due to the emergence of a large thermal resistance in the sample, which we have measured and used to model the observed heat capacity depression. Our measurements of the superfluid thermal resistivity are a factor of ten larger than previous measurements by Baddar et al.

Original languageEnglish
Pages (from-to)495-505
Number of pages11
JournalJournal of Low Temperature Physics
Issue number1-2
StatePublished - Jan 2004


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