Sound conversion phenomena at the free surface of liquid helium. II. Experimental determination of acoustic coefficients and surface absorption coefficients
The acoustic coefficients of reflection, transmission, and transformation of first-, second-, and gas sound waves incident normally on the free surface of liquid helium have been determined. The experimental results are compared with the theory developed in Part I of this paper. It is shown that equilibrium theories of boundary conditions disagree with the experiments. Nonequilibrium theories, however, which take into account that mass and energy transport processes occur at the liquid-vapor interface of helium II, lead to a very good description of the experimental data below 2 K. Within experimental accuracy the measurements fully confirm several kinetic models of evaporation and energy transport processes. Near the lambda point, deviations from the theory have been found which might be attributed to influences of critical phenomena. The surface absorption coefficients of first-, second-, and gas sound waves could be deduced from the experimental data on the acoustic coefficients, and it is shown that, in agreement with the theory, appreciable energy dissipation occurs at the free surface of helium II when a second-sound or a gas sound wave is incident.
- Research Organization:
- Institut fuer Physik, Johannes-Gutenberg Universitaet, Mainz, West Germany
- OSTI ID:
- 5959621
- Journal Information:
- J. Low Temp. Phys.; (United States), Vol. 51:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
HELIUM II
SECOND SOUND
SOUND WAVES
BOUNDARY CONDITIONS
ENERGY TRANSPORT
EXPERIMENTAL DATA
INTERFACES
KINETIC EQUATIONS
LIQUIDS
MASS TRANSFER
REFLECTION
SURFACES
TRANSMISSION
ULTRALOW TEMPERATURE
DATA
EQUATIONS
EVEN-EVEN NUCLEI
FLUIDS
HELIUM 4
HELIUM ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUMERICAL DATA
QUANTUM FLUIDS
STABLE ISOTOPES
640450* - Fluid Physics- Superfluidity