HE-3 FILM FLOW ON A ROUND RIM BEAKER

The superfluid properties of thin (100-150 nm) of He-3 were investigated by measuring the rate at which a beaker of liquid He-3 emptied itself through the adsorbed film, with the film thickness delta decreasing as the level dropped. A beaker rim with a semicircular cross-section was used to provide a well defined geometry and to avoid the effects of small scratches that may have affected earlier experiments. The film thicknesses were determined by Atkins' oscillaton measurements of He-4 films on the same surface. The superfluid transition temperature in the film T(c)F was suppressed below the bulk value T(c)B and was close to being described by 2delta/xi(T(c)F) = pi, as expected for A-phase. The critical current density was more than an order of magnitude smaller than expected for pair-breaking. When a He-4 monolayer was adsorbed on the substrate, there was no suppresson of T(c)F and the critical current density, was much larger. With or without the He-4 monolayer an abrupt decrease in the flow rate was observed as the film thinned, which may be associated with the B to A-phase transition that should occur.