Studies of Wall-film Superfluidity in Helium-3/helium-4 Mixtures

Studies of Wall-film Superfluidity in Helium-3/helium-4 Mixtures

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The main purpose of the project is to study the onset and growth of superfluidity in a thin 3He/4He mixture film (wall film) near the surface of a container. The main experimental technique is to use a thin quartz crystal immersed in a liquid 3He/4He mixture, vibrating in a transverse mode at frequencies near 25M, 35M and 105MHz. By measuring the resonant frequency and peak amplitude as a function of temperature from 0.5 K to 1.5 K, the acoustic impedance of the mixture can be obtained. The experimental results can be used to study the superfluidity properties of the wall film. A capacitor in the experimental cell has been used to measure the dielectric constant of the mixtures for reference. Experiments have been conducted having mixtures with 3He mole fractions of 0.750, 0.705, 0.6735 and 0.644. Results are analyzed based on dynamic Kosterlitz-Thouless theory and local continuum theory. The analysis shows that the wall film has a dynamic Kosterlitz-Thouless type superfluid transition and can be treated as a quasi-2D system. The results of simulation based on a modified hydrodynamic model show good agreement with the experimental results.The interface is chosen as the reference point. The 3He mole fraction at the interface is chosen to be the 3He mole fraction along the phase separation line in the phase diagram at saturated vapor pressure, and the pressure at the interface isanbsp;...

Title:Studies of Wall-film Superfluidity in Helium-3/helium-4 Mixtures
Author:Weimin Deng
Publisher:ProQuest - 2007


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