Studies of the flow properties of superfluid /sup 3/He and of the superfluid density of /sup 4/He films in restricted geometries

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5818562

Crooker, B C

The torsional oscillator technique was used to study the properties of several superfluid systems. One series of experiments involved the study of /sup 3/He-B, performing oscillatory flow through 5 and 2 micron orifices which were mounted across annular flow channels. A single dissipation feature involving the destruction of superflow through the orifice was observed. Critical velocities calculated from the data scale as the inverse of the orifice diameter are found. Vortices are discussed as a possible dissipation mechanism. The addition of a dc flow through the orifice was found to have no observable effect. A second experiment was designed to study rho/sub n/ in /sup 3/He-A, which is known to be anisotropic. From these experiments estimates can be made of rho/sub n/ parallel and perpendicular to the anisotropy axis. In addition, evidence was found for the presence of persistent currents lasting at least ten minutes. The third experiment involves the study of rho/sub n/ in very thin /sup 4/He films adsorbed on Vycor glass. Due to the highly interconnected nature of the 70 A pores in this system, the temperature dependence of rho/sub n/ in the critical region was found previously to be similar to that observed in bulk. Films with estimated superfluid densities as low as 3 x 10/sup 18/ atoms/cm/sup 3/ have been studied. At densities below 10/sup 19/ atoms/cm/sup 3/ and transition temperatures in the vicinity of 10 mK, a crossover to more mean-field like behavior is observed. The final experiment discussed was designed to detect superfluidity in /sup 3/He confined in Vycor glass. No superfluid transition was observed in our experiments placing limits on the possible superfluid densities in the glass.

• OSTI ID: 5818562
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DENSITY
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FILMS
FLUID FLOW
FLUIDS
HELIUM 3
HELIUM 3 A
HELIUM 3 B
HELIUM 4
HELIUM II
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
NUCLEI
PHYSICAL PROPERTIES
QUANTUM FLUIDS
STABLE ISOTOPES
SUPERFLUIDITY
VYCOR