Supercooling Helium Vapor: Nucleation and Fog Formation Induced by Strong Evaporation
| Autor: | A. T. Nguyen Le, Peter Taborek, J. E. Rutledge, Justin Burton |
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| Rok vydání: | 2004 |
| Předmět: |
Mass flux
Materials science Vapor pressure Evaporation Nucleation chemistry.chemical_element Thermodynamics Condensed Matter Physics Atomic and Molecular Physics and Optics Physics::Fluid Dynamics Condensed Matter::Soft Condensed Matter chemistry Metastability General Materials Science Physics::Atomic Physics Wetting Supercooling Physics::Atmospheric and Oceanic Physics Helium |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 0022-2291 |
| DOI: | 10.1023/b:jolt.0000012567.24143.e9 |
| Popis: | We have studied heterogeneous nucleation of liquid 4He on cesiated surfaces using calorimetric techniques. Nucleation kinetics are strongly influenced by wetting properties. Since liquid 4He does not wet cesium below 2K, substantial supercooling of the vapor is expected on theoretical grounds. Experimentally, however, we have been unable to detect any supercooling in our cells. This may be due to microscopic defects in the Cs coating, which in turn may be related to the fact that we have been unable to find a cell construction material which is wetted by Cs. Somewhat paradoxically, it is possible to supercool helium vapor even in a container made of conventional wetted materials by imposing a large heat and mass flux from the liquid to the vapor across the bulk liquid-vapor interface. When evaporation is sufficiently strong, the vapor above the liquid becomes unstable, and forms a dense fog. Videos of this process show that the fog front propagates rapidly from very near the liquid-vapor interface upward into the vapor. Fog formation near the liquid interface implies that the vapor is in a supercooled metastable state. Qualitative ideas from non-equilibrium thermodynamics and kinetic theory are used to explain this phenomenon. |
| Databáze: | OpenAIRE |
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