Helium II film transfer

Abstract

Helium, the lightest of the noble gases, is the most difficult of all to liquify. Despite this, since the first liquefaction of helium by Kamerlingh Onnes (1908) the properties of the liquid have been extensively investigated. The continued interest in the liquid after almost six decades is due to its unique properties, the most striking is the superfluidity exhibited below 2.19°k. one of the most clear-cut examples of superfluid flow is that of the saturated helium film which is formed on all solid surfaces in contact with the liquid. Although fluid transfer by the film has been the subject of a great many experimental and theoretical scrutinies, many aspects of the phenomenon have remained enigmatic. In particular, the variability of the rate of superfluid transfer through the film under various experimental conditions has never been satisfactorily explained. The present study was undertaken to clarify this situation, and to provide information on which to base a hydrodynamic theory of the film. Part of the research has already been reported (Matheson and Tilley, 1965; Allen and Matheson, 1965). Both a knowledge of the salient properties of liquid helium and an understanding of the various theories of superfluidity are necessary of the idiosyncrasies of the helium film are to be resolved. It would seem appropriate, therefore, to review these particular facets of the helium problem so that the ensuing investigation of the film can be seen in its proper perspective.