Testing the performance of a cryogenic visualization system on thermal counterflow by using hydrogen and deuterium solid tracers

An experimental apparatus has been designed to analyze by visualization cryogenic flows of liquid He-4 and consequently address unresolved problems of quantum turbulence. The newly implemented flow visualization setup is described and its specific features discussed. Thermal counterflow experiments have been performed and the motion of solid hydrogen and deuterium tracers studied by using the particle tracking velocimetry technique in order to probe the system capabilities. It is shown that the obtained results are consistent with the two-fluid model describing the behavior of superfluid 4He. A number of technical and fundamental issues, such as particles' aggregation, role of rotating particles in counterflow and evidence of non-Gaussian distribution of tracers' velocities, are also discussed. The apparatus appears to be well-suited to the task of analyzing cryogenic flows and potentially capable of obtaining new results stimulating further understanding of the underlying physics. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4719917]