Early Superfluidity in Cambridge, 1936 to 1939
My work on superfluidity in the Mond Laboratory in Cambridge began in 1936 with an attempt to measure the thermal conductivity of HeII. Very luckily, as it transpired, I had no other thermometer than the saturated vapour pressure of the liquid. Measuring heat flow along a capillary tube of liquid showed that it was not proportional to temperature gradient, but that the “conductivity” became greater with smaller gradient, approaching infinity as the gradient approached zero. Pressure-driven flow showed that the rate became less and less dependent on pressure as the size of flow tube diminished; so no true “viscosity”. Then with small heat flow in the smallest tubes, the movement of liquid levels indicated actual fluid flow up the temperature gradient, and finally, by accident, a fountain was seen. The thermodynamic reverse of the fountain was then observed in Oxford, as was the mobile HeII film. Finally, in 1939 a heat pulse was observed to travel along a capillary at a speed of the order of 104 cm sec-1, which was a precursor of second sound. The outbreak of war brought an abrupt end to three hectic years which demonstrated many of the key superfluid phenomena.
KeywordsHeat Flow Liquid Helium Saturated Vapour Pressure Heat Pulse Measure Heat Flow
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- 7.E. Ganz, An attempt to measure the velocity of propagation of heat in liquid Hell, in: “Proc. Cam. Phil. Soc. ” Vol. XXXVI, Part I, 127, 1939.Google Scholar