Persistent Currents in SuperfluidHe3-B

Observations of persistent currents in superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-$B$ have been made with use of a recently developed ac gyroscope technique. The persistent currents are generated in a toroidal region filled with a fibrous material with average pore size of ${10}^{-2\mathrm{}}$ cm. In this geometry, a mean critical velocity of 7 × ${10}^{-2\mathrm{}}$ cm/sec was observed. To within experimental error, no decay of the currents was observed for periods of over one hour.