Pvt Relations in Solid HE3 and Solid HE4 Flow Measurements with Superfluid Helium

摘要

The gravitational flow of superfluid helium through 'large' (internal diameter greater than 0.01 cm) capillaries at 0.4K has been studied. The primary purpose of this experiment was to find the form of the pressure gradients as a function of fluid velocity. As expected, a critical velocity, below which the pressure gradient was zero, was observed. Over a small range of velocities the pressure grandient varied nearly linearly with velocity, and at higher velocities it varied as the velocity squared. We are attempting to explain these results in terms of the creation of vortex rings at the capillary wall. The experiments are being continued with straight glass capillaries instead of spiralled metal ones in hopes of obtaining more consistant results. An improved apparatus has been developed to continue measurements begun at Yale University with Air Force support on the PVT relations in solid helium (AD-408 479). Microwave cavities are being used to measure the pressure as well as the density. An experiment to study the propagation of second sound in rotating rectangular resonators is also described. We hope to measure the Magnus force on superfluid vortices by this technique. (Author)