Helium II Film Transport. II. The Role of Surface Finish

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Abstract
The effect of surface finish has been studied by comparing transport rates measured on four metal beakers (aluminum, nickel, stainless steel, and nickel-silver), before and after they had been "superfinished." Deliberately roughened surfaces were employed in similar control experiments on glass. Measured values of beaker microfinish are reported for comparison with flow rates. The data obtained with these specimens, as well as with a nickel beaker whose inner wall was broached to provide, in effect, a capillary covered surface, are consistent with the hypothesis that transport rates adjust to the prevailing microscopic perimeter and do not require the added hypothesis of anomalous flow in surface cracks. A scheme for estimating the difference between macro- and micro-perimeter is proposed, and the flow data are found to be consistent with its predictions. These include the result that a large increase in surface roughness may not imply a very large change in the microscopic perimeter "seen by the film."

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