Sound propagation in a superfluid helium filled porous solid: theory and experiment

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

OSTI ID:7020631

Baker, S R

The propagation of sound in a superfluid helium filled porous solid was investigated theoretically and experimentally. Motivated by the (classical ) Biot theory for the propagation of elastic waves in a fluid saturated porous solid, a set of linearized two fluid equations, averaged over the fine structure of the solid, was developed. From these were derived dispersion relations for the transition from first sound to fourth sound (c/sub 1/ ..-->.. c/sub 4/) and from second sound to diffusion (c/sub 2/ ..-->.. diffusion) in a superfluid helium filled porous solid as the viscous drag on the normal component varies from zero to infinity. The speed and attenuation of the c/sub 1/ ..-->.. c/sub 4/ mode was measured from 1.1K to 2.15 K under saturation vapor pressure (SVP) in three packed powder samples ranging from 1 to 25 ..mu.. nominal grain diameter and in three sintered bronze sphere samples ranging from 75 to 500 ..mu.. nominal diameter, covering both sides of the transition. The speed and attenuation of the c/sub 2/ ..-->.. diffusion mode was measured from 1.4 K to 2.15 K under SVP in the 500 ..mu.. diameter sample, covering the c/sub 2/ side of the transition. This experiment marks the first time the Biot structural factor delta of a porous solid has been directly determined.

• Research Organization: California Univ., Los Angeles (USA)
• OSTI ID: 7020631
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DIFFUSION
DISPERSION RELATIONS
FLUID FLOW
MATERIALS
POROUS MATERIALS
SOLIDS
SOUND WAVES
SUPERFLUIDITY
VISCOUS FLOW
WAVE PROPAGATION