Spatial distribution of vortices and anisotropy of mutual friction in rotating He II

Journal Article · Thu Mar 01 04:00:00 EST 1984 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.29.2489· OSTI ID:6778411

Mathieu, P; Placais, B; Simon, Y

Accurate measurements of the attenuation of second sound in a rotating parallelepipedic cavity are reported. The cavity, which is used as a half-wave resonator, can be tilted about one of its symmetry axes so that the two large faces make an arbitrary angle theta with the angular velocity Omega-arrow-right. A continuum model is developed predicting that vortices, at equilibrium, must bend near the inclined plane walls, and terminate perpendicular to the boundary. The curvature of the vortices, otherwise parallel to Omega-arrow-right and uniformly distributed, takes place over a characteristic depth d/sub 0/ = 0.29..cap omega../sup -1/2/ mm which is small compared with the dimensions of the cavity. The resulting changes in density and orientation of vortex lines, though localized near the walls, measurably affect the detailed dependence on both ..cap omega.. and theta of the quality factors of resonant modes. Experimental results taken with two fundamental modes of the cavity support our model. As a by-product of these measurements we obtain information about the angular dependence of mutual friction. A small but clearly nonzero attenuation was observed for a second sound propagated in the direction of vortex lines. This axial attenuation can be described by introducing, besides the first mutual-friction parameter B, another dissipative coefficient B'' which is about 2.5% of B (at 1.9 K). In Hall and Vinen's equations of motion of He II this B'' should represent the axial component (along Omega-arrow-right) of the mutual-friction force. In this work we have deliberately ignored the intricate problem of metastable states, trying to get rid of them in experiments; thus reported results all refer to states of (or near) thermodynamic equilibrium.

• Research Organization: Groupe de Physique des Solides de l'Ecole Normale Superieure (Laboratoire associe au Centre National de la Recherche Scientifique), 24 rue Lhomond, F-75231 Paris Cedex 05, France
• OSTI ID: 6778411
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 29:5; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
ATTENUATION
CAVITY RESONATORS
DATA
DIFFERENTIAL EQUATIONS
ELECTRONIC EQUIPMENT
EQUATIONS
EQUATIONS OF MOTION
EQUIPMENT
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
FLUIDS
FRICTION
HELIUM 4
HELIUM II
HELIUM ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
MOTION
NUCLEI
NUMERICAL DATA
PARTIAL DIFFERENTIAL EQUATIONS
QUANTUM FLUIDS
RESONATORS
ROTATION
SECOND SOUND
STABLE ISOTOPES
VORTICES