A simple model of helium desorption kinetics

Abstract

Recent experiments studying helium desorption by heat pulse techniques are interpreted in terms of a model in which the film is assumed to have the thermodynamic properties of bulk liquid helium, and the vapor is described by kinetic theory. Equations for energy and mass conservation are sufficient to determine the behavior of the system. The most important parameter in the model turns out to be the interfacial thermal resistance between the film and vapor, R_v,. This quantity varies over orders of magnitude, and is found to govern a number of the phenomena observed in the experiments. In addition to resolving some of the puzzles arising in desorption experiments, the model serves to clarify the relationship between this work and an earlier body of work concerning the Kapitza resistance in adsorbed films. Predictions of the model compare remarkably well to the results of both types of experiment.

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