An apparatus for measuring the attenuation and velocity dispersion in sound in a magnetic field at low temperatures

✍ Scribed by V.I. Beletskii; A.P. Korolyuk; M.A. Obolenskii

• Publisher: Elsevier Science
• Year: 1973
• Tongue: English
• Weight: 599 KB
• Volume: 13
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(73)90268-3

✦ Synopsis

would need to be trapped in order to bring the viscosity results back to the correct value. A clue to this can be found from observations of the specific heat 4 and adsorption characteristics 5 of He 3-tte 4 mixture films, from which it was inferred that the He 3 component of such films resides mainly on the free surface. The few He 3 atoms trapped in the sinter may therefore be quite rapidly transported on the film surface as it flows down into the viscometer, leaving essentially pure He 4 in the sinter.

These observations raise interesting fundamental questions relating to the true equilibrium configuration in capillary rise experiments, and to the transport of He 3 atoms in a superfluid helium film, which suggest several experimental investigations. Whatever their outcome, it is clear that from a practical point of view it is essential that great care should be taken in the use of sintered copper heat exchangers, both with pure helium and with solutions, when it is vital to know the amounts of helium distributed in various parts of the system. This observation is worth emphasizing, since it does not seem to be universally appreciated.