CXXXI. Film flow and the behaviour of he cryostats below the λ-point

Abstract

Abstract A description is given of experiments which confirm in detail the mechanism proposed by Rollin and Simon concerning the behaviour of the helium film in pumping tubes of low temperature cryostats. In particular the temperature distribution along these tubes which, as a result of the film, is of an unusual nature, was determined. Experiments were carried out both on tubes having uniform cross sections and tubes containing a constriction, and it is shown how the above mechanism can be used to measure film transfer rates in each case. The results are finally discussed from the point of view of the design of helium cryostats.