Discrete Flow Rates of the Helium Film

Measurements of the helium-film flow rates over a stainless steel substrate have been made using the heat-transport method of Bowers, Brewer, and Mendelssohn. The moving film from a reservoir is vaporized inside a copper box at the top of the stainless steel capillary in a closed system, by electrical heating. The vapor recondenses in the isothermal reservoir. On any day's run, the rate was constant and reproducible to within 1%. The complete range of flow rates observed at 1.2°K on separate days was about 50%. Seven discrete rates were in fact observed in 18 runs nearly equally spaced at intervals of 0.83×${10}^{-5\mathrm{}}$ ${\mathrm{cm}}^2$ ${\sec }^{-1\mathrm{}}$. At present, no theory predicts discrete flow rates.