チョウリュウドウ ヘリウム 4チュウ ノ リョウシ カネンセイリツ ノ ソクテイ

The viscosity of liquid ^4He has been measured by means of a high-Q torsional oscillator at temperatures between 1.8 K and 2.8 K under saturated vapour pressure. Below the superfluid transition temperature, the eddy viscosity in addition to the viscosity caused by the normal fluid component was observed when the velocity of cell-wall exceeded the critical velocity. The magnitude of the critical velocity depends on the roughness of the cell wall. In the case of a cell with rough wall, the critical velocity is low compared with a cell with smooth wall

エキタイ 3HE エノ 4HE ヨウカイド ノ ソクテイ

The solubility of ^4He in liquid ^3He have been measured from 500mK to 25mK by detecting tiny amount of ^4He-film appearing below the phase- separation temperature, using a dielectric technique. The capacitor to detect the ^4He-film has narrow gap, ～2μm, between electrodes. To prevent the film flow of ^4He out of the cell through the filling tube, a valve tight for the superfluid was attached to the cell. Saam et al. proposed a equation on ^4He solubility in liquid ^3He predicting the exponential decrease to almost zero, 10^ ppm, at 30mK. Our experimental results indicated that the ^4He solubility at very low temperatures in much larger that their prediction, which presents a new problem on the interaction between ^4He and ^3He in the dilute solution of ^4He in liquid ^3He