ENERGY DISSIPATION IN FLOW OF SUPERFLUID HELIUM AND CRITICAL VELOCITY

A study of the energy dissipation in the flow of the superfluid component of liquid helium in wide chambers (6-1 mm) and slits (150-15 μm) is performed by means of a calorimetric technique. In the experiments the normal component is clamped by means of superleaks. The critical velocities obtained from these experiments are discussed and compared with those of other experiments; it is shown that the superfluid critical velocity varies with the fourth root of the channel diameter and is temperature independent. © 1969.