Heat transport through He II is summarized in terms of the hydrodynamics of the two-fluid model. With increasing thermal flux, three regimes are identified, depending on the development of vorticity in the superfluid component and the development of a classical turbulence in the normal component. Calculation of summary curves of thermal gradient as a function of thermal flux is explained, and graphical results presented. An estimate of the limiting thermal flux for inception of vapour formation within He II is made, and time-dependent effects are discussed. The presentation is oriented towards use of He II in the nominal range from 1.5 to 2.1 K; special effects near the 2-point (2.17 K) are not considered, nor are conductivity changes below about 0.6 K due to rapid decreases of roton contributions.
Heat transport through helium II V. Arp
Technology appears to be moving towards the use of superfluid helium for cooling research devices, for example, superconducting magnets, linear accelerators, etc. Though many studies have been made of the basic physics of this unique fluid, there appears to be no satisfactory engineering-oriented review of its behaviour as a heat transfer medium. A preliminary review of the subject establishes that there are two separate aspects which must be considered. The first involves the temperature difference between a heated solid and the superfluid helium which cools it. This is commonly known as the Kapitza resistance, and is the subject of an article by N. S. Snyder. 1 The second concerns heat transfer through the bulk of the helium, where significant temperature gradients can build up under high heat loads. This latter aspect is tlie subject of this paper. We consider only temperatures in the approximate range from 1.5-2.1 K, wherein it seems probably that most large devices would operate.
* To obtain the entropy in SI units, (d/kg K), multiply entries in this column by 108 .
1" To obtain the viscosity in SI units, (Ns/m=), multiply entries in this column by 10 -7 .