Pvt Relations in Solid He-3 and Solid He-4, Flow Measurements with Superfluid Helium

摘要

Studies were made of the flow of liquid helium in round capillaries and orifices with diameters between 70 and 300 microns. Gravitational flow is caused by a mechanical displacement of the liquid from an equilibrium level. This technique was used in a series of experiments on the flow of helium at 0.4K in an attempt to discover the macroscopic flow properties of pure superfluid in moderate sized channels. The experimental conditions were chosen as a reasonable approximation to isothermal flow of pure superfluid. Results are in agreement with previous experiments with liquid helium, namely that below a certain critical velocity the superfluid flows with no dissipation, that is with zero pressure gradient. (Author)