科研之友
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摘要
The thermomechanical effect in superfluid helium is used to create an initial chemical potential difference Delta mu(0) across a solid He-4 sample. This Delta mu(0) causes a flow of helium atoms from one reservoir filled with superfluid helium, through a sample cell filled with solid helium, to another superfluid-filled reservoir until chemical potential equilibrium between the reservoirs is restored. The solid helium sample is separated from each of the reservoirs by Vycor rods that allow only the superfluid component to flow. With an improved technique, measurements of the flow F at several fixed solid helium temperatures T have been made as a function of Delta mu in the pressure range 25.5-26.1 bar, and measurements of F have been made as a function of temperature in the range 180 < T < 545 mK for several fixed values of Delta mu. The temperature dependence of the flow above 100 mK shows a reduction of the flux with an increase in temperature that is well described by F = F-0* [1 - K exp(-E/T)]. The nonlinear functional dependence F similar to (Lambda mu)(b), with b < 0.5 independent of temperature but dependent on pressure, documents in some detail the dissipative nature of the flow and suggests that this system demonstrates Luttinger liquid-like one-dimensional behavior. The mechanism that causes this flow behavior is not certain, but is consistent with superflow on the cores of edge dislocations.
- 出版日期2014-10-16
