Visualization study of counterflow in superfluid helium-4 using metastable helium molecules
| Autor: | Guo, Wei, Cahn, Sidney B., Nikkel, James A., Vinen, William F., McKinsey, Daniel N. |
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| Rok vydání: | 2010 |
| Předmět: | |
| Zdroj: | Phys. Rev. Lett. 105, 045301 (2010) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevLett.105.045301 |
| Popis: | Heat is carried in superfluid He-4 by the motion of the normal fluid$^{1}$, a counterflowing superfluid component serving to eliminate any net mass flow. It has been known for many years that above a critical heat current the superfluid component in this counterflow becomes turbulent. This turbulence takes the form of a disorganized tangle of quantized vortex lines and is maintained by the relative motion of the two fluids$^{2-3}$. It has been suspected that the normal fluid may also become turbulent$^{4}$, but experimental verification is difficult without a technique for visualizing the flow. Here we report a series of visualization studies on the normal-fluid component in a thermal counterflow performed by imaging the motion of seeded metastable helium molecules using a laser-induced-fluorescence technique$^{5-8}$. We present evidence that the flow of the normal fluid is indeed turbulent, at least at relatively large velocities. Thermal counterflow in which both components are turbulent presents us with a new and theoretically challenging type of turbulent behaviour. Comment: 6 pages, 4 figures. Supplementary information is included. |
| Databáze: | arXiv |
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