Particles for tracing turbulent liquid helium

摘要

We address the problem of making quantitative measurements of local flow velocities in turbulent liquid helium, using tracer particles. We survey and evaluate presently available particles and previous work to establish the need to develop new particles for the purpose. We present the first practical solution for visualizing fluid motions using a suspension of solid hydrogen particles with diameters of about 2 mu m. The hydrogen particles can be used to study flows with Taylor-microscale Reynolds numbers between 85 and 775. The particles can be used equally well with the PIV, LDV, or particle-tracking techniques.