Applications of a Laser Doppler Velocimeter and Some Visualization Methods to the Measurement of He II Thermo-Fluid Dynamic Phenomena

Abstract

We have been engaged in the development of the application techniques of a laser Doppler velocimeter (LDV) and some flow visualization methods, a tracer method and a laser holography interferometer method, for the measurement of He II thermo-fluid dynamic phenomena. An LDV was applied to directly measure the normal fluid component velocity in a thermal counterflow jet by using hydrogen-deuterium micro solid particles as tracer particles. He II thermal counterflow jet was also visually studied by tracer method by adopting hydrogen-deuterium solid particles and hollow glass spheres both of which are neutrally buoyant in He II. The translational motion of a large-scale vortex ring was also investigated by this method. Some wave phenomena in He II were also visually investigated by applying a laser holography interferometer method. In this report, the application techniques of these methods are described and some typical results are presented to demonstrate their validity and to point out some problem areas.