THERMAL-CONDUCTIVITY OF HE-4 NEAR THE SUPERFLUID TRANSITION IN A RESTRICTED GEOMETRY

We report measurements of the thermal conductivity of He4 at vapor pressure confined in a glass capillary array of thickness 3 mm with holes 2μm in diameter. The finite geometry rounds the superfluid transition, resulting in a finite thermal conductivity at the bulk transition temperature Tλ. Below Tλ the thermal conductivity becomes effectively infinite when the bulk correlation length becomes small compared to the size of the confining holes. © 1995 The American Physical Society.