Direct measurement of vortex diffusivity in thin films of /sup 4/He

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:5330348

Adams, P W

A high Q torisonal oscillator was used to measure the superfluid density and excess dissipation in thin films of /sup 4/He as a function of temperature. These measurements were compared to the dynamic theory of the Kosterlitz-Thouless transition via numerical fits to the data. Nonlinear effects were investigated by systematically increasing the amplitude of the oscillation and comparing the resulting changes in the film's superfluid density and dissipation to theory. The effects of rotation on the Kosterlitz-Thouless transition were also studied and rotation-induced dissipations were measured. These yielded the first direct measurements of vortex diffusivity, D, as a function of temperature through the superfluid transition. It was found that D was a rapidly varying function in the region near the transition. It was very small well below the transition, increased to order h/m at the static transition temperature, and appeared to diverge at the point where the superfluid density vanished. The diffusivity also appeared to be insensitive to the presence of /sup 3/He impurities and to the nature of the substrate.

• Research Organization: Rutgers--the State Univ., New Brunswick, NJ (USA)
• OSTI ID: 5330348
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DIFFUSION
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FILMS
FLUID FLOW
FLUIDS
HELIUM 3
HELIUM 4
HELIUM II
HELIUM ISOTOPES
IMPURITIES
ISOTOPES
LIGHT NUCLEI
MOTION
NONLINEAR PROBLEMS
NUCLEI
QUANTUM FLUIDS
ROTATION
STABLE ISOTOPES
SUPERFLUIDITY
THIN FILMS
VORTEX FLOW