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Experimental study of helium-4 film flow at the Kosterlitz-Thouless Transition and wetting in helium-4 films near T(lambda)
Abstract
Thermal conductivity measurements were performed on $\sp4$He films adsorbed on two substrates to test the role that substrate geometry may have on dynamic measurements at the Kosterlitz-Thouless Transition. For films having thicknesses less than the transition thickness, the evolution of the temperatures as a function of film thickness, at fixed heater power, were observed to be qualitatively similar for both substrates. For each substrate, the thermal conductivity of superfluid films followed the power law dependence on heater power consistent with the measurements of Maps and Hallock and suggests that the basic features of the Kosterlitz-Thouless transition are not fundamentally dependent on the two geometries. In a second experiment a search for wetting anomalies in a saturated helium film at temperatures near the bulk transition temperature is made using a capacitive technique. The wetting transition observed by Taborek and Senator is not observed, and under optimal operating conditions, the film thickness is constant as a function of temperature to within one atomic layer for temperature sweeps spanning the bulk transition temperature. Film thinning consistent with that observed by Taborek and Senator does occur when thermal gradients are imposed on the experimental cell.
Subject Area
Condensed matter physics|Mechanical engineering
Recommended Citation
Dionne, Robert Joseph, "Experimental study of helium-4 film flow at the Kosterlitz-Thouless Transition and wetting in helium-4 films near T(lambda)" (1990). Doctoral Dissertations Available from Proquest. AAI9110125.
https://scholarworks.umass.edu/dissertations/AAI9110125