Formation of a Mesa Shaped Phonon Pulse in聽Superfluid 4He
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- 作者：I. N. Adamenko ; K. E. Nemchenko and V. A. Slipko
- 关键词：Superfluid helium ; Phonon pulse ; Second sound ; Simple wave
- 刊名：Journal of Low Temperature Physics
- 出版时间：May, 2010
- 出版年：2010
- 期刊代码：20_00222291
- 类别：law
- 卷：159
- 期：3-4
- 页码：492-514
- 数据来源：sp
摘要
We present a theory for the formation of a mesa shaped phonon pulse in superfluid 4He. Starting from the hydrodynamic equations of superfluid helium, we obtain the system of equations which describe the evolution of strongly anisotropic phonon systems. Such systems can be created experimentally. The solution of the equations are simple waves, which correspond to second sound in the moving phonon pulse. Using these exact solutions, we describe the expansion of phonon pulses in superfluid helium at zero temperature. This theory gives an explanation for the mesa shape observed in the measured phonon angular distributions. Almost all dependencies of the mesa shape on the system parameters can be qualitatively understood.