35. Critical velocities of 4He in a superfluid flow through a glass capillary of 260 microns diameter
✍ Scribed by F.A. Staas; R. De Bruyn Ouboter
- Publisher
- Elsevier Science
- Year
- 1958
- Weight
- 67 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0031-8914
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✦ Synopsis
LIgUID HELIUM S 143 heat transport by liquid 4He through a narrow slit at eleven temperatures between 1. I°K and 2. I°K for values of AT up to 1000 millidegrees. The slit (1.9 cm long and 2 microns wide) connects two reservoirs of liquid helium, one thermally isolated and fitted with a heater, the other intimately coupled to the helium bath. Two ½-watt carbon resistors serve as thermometers. All measurements are made with the isolated reservoir completely filled. Upon heating, the fountain pressflre compresses the liquid in this reservoir causing a drop of the liquid level in the colder (reference temperature) reservoir. Observations of this level change together with information on the liquid density 1) and compressibility 2) allow a calculation of Pf.
The results show two important divergences from previous similar experiments 3) : (1) initial slopes of heat current vs AT are not linear, but concave upward; and (2) plots of heat current vs PI are also concave upward in disagreement with the Allen-Reekie rule. These results will be discussed in relation to present theories.