Superfluid Helium in Restricted Geometries

Superfluid flow in restricted geometries is discussed in the framework of the Landau quasiparticle theory. A recently observed linear temperature dependence of ${\rho }_n$ for helium flowing in powders is explained in terms of a model geometry which can be fairly described as "zero-dimensional." Further experiments are suggested for exploring other features of restricted geometries and testing the zero-dimensional model.