Non-linear, parametric generation of sound by resonant mode conversion

Thesis/Dissertation · Sat Jan 01 04:00:00 EST 1977

OSTI ID:5126725

Garrett, S L

When non-linear terms are included in the two fluid hydrodynamic description of superfluid helium-4, first sound (pressure-density waves) and second sound (temperature-entropy waves) are coupled. The interaction of two second sound waves to produce a propagating first sound wave is shown to occur at a specific angle which makes the point of intersection of the second sound waves travel at the speed of first sound. The growth of the mode converted first sound wave is calculated with and without attenuation of the primary (second sound) waves from 1.2/sup 0/K to 2.15/sup 0/K and from saturated vapor pressure to twenty atmospheres. An experiment to observe this mode conversion process in a waveguide to rectangular cross-section is described. In the waveguide the intersection angle of the second sound waves is controlled by the ratio of the frequency of the higher order propagating mode of second sound to the cut-off frequency for that mode. Experimental measurements show that the resonant conversion of second sound to first sound in the waveguide occurs at the theoretically predicted frequency to within experimental error (0.1% to 0.2%) between 1.14/sup 0/K and 2.04/sup 0/K at saturated vapor pressure. The amplitude of the mode converted first sound is found to exhibit a quadratic dependence on the amplitude of the primary wave which is characteristic of a second order effect over the same range of temperatures.

• Research Organization: California Univ., Los Angeles (USA)
• OSTI ID: 5126725
• Country of Publication: United States
• Language: English

Related Subjects

640450* -- Fluid Physics-- Superfluidity
657004 -- Theoretical Physics-- Acoustics-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACOUSTICS
AMPLITUDES
COUPLING
DATA
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
FLUID MECHANICS
FLUIDS
HELIUM 4
HELIUM II
HELIUM ISOTOPES
HYDRODYNAMICS
INFORMATION
ISOTOPES
LIGHT NUCLEI
MECHANICS
MEDIUM PRESSURE
NUCLEI
NUMERICAL DATA
PHYSICAL PROPERTIES
QUANTUM FLUIDS
SECOND SOUND
SOUND WAVES
STABLE ISOTOPES
THERMODYNAMIC PROPERTIES
ULTRALOW TEMPERATURE
VAPOR PRESSURE
WAVE PROPAGATION
WAVEGUIDES