Flow of Liquid Helium through Fine Channels

The use of etched copper membranes for studying the flow properties of liquid helium is described. In liquid helium II the velocity of flow is found to be proportional to the n th power of the pressure difference, where the exponent n has the value 0.22 from 1.15° K. to 1.9° K. and increases slightly near the λ-point. Some determinations of the viscosity of liquid helium I give results in general agreement with earlier work, no indication of non-classical or superfluid flow being apparent either immediately above the λ-point or at higher temperatures.