Quasiequilibrium distribution function of anisotropic phonon systems and the interaction of pulses of low-energy phonons in superfluid helium

Journal Article · Mon Aug 01 04:00:00 EDT 2005 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.72.054507· OSTI ID:20719298

Adamenko, I N ^[1]; Kitsenko, Yu A; Nemchenko, K E; Slipko, V A ^[1]; Wyatt, A F.G. ^[2]

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1. Karazin Kharkov National University, Svobody Sq. 4, Kharkov, 61077 (Ukraine)
2. School of Physics, University of Exeter, Exeter EX4 4QL (United Kingdom)

The phenomenon of a hot line forming in liquid helium was observed in experiments carried out in the University of Exeter (UK). It arises when two phonon pulses interact and this is theoretically investigated in this paper. To develop the theory we start from the exact quasiequilibrium distribution function that describes anisotropic phonon systems such as a phonon pulse in superfluid helium. This is related to the approximate distribution function, which is more physically intuitive and was used earlier. The local equilibrium distribution function for phonons in the region of a hot line is obtained from the distribution functions for the phonons in the two interacting pulses. In order to explain the results of experiments, we analyze the effect of different pressures when the angle between the two moving pulses in superfluid helium is constant and also the effect of different angles at the saturated vapor pressure. The conditions suitable for the creation of a hot line are found. The results of the calculations are compared with the experimental data.

• OSTI ID: 20719298
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 5 Vol. 72; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANISOTROPY
DISTRIBUTION FUNCTIONS
EQUILIBRIUM
HELIUM
HELIUM 4
LIQUIDS
PHONONS
PULSES
SUPERFLUIDITY
VAPOR PRESSURE