On the suprathermal distribution in an anisotropic phonon system in He II

Adamenko, I. N.; Nemchenko, K. E.; Wyatt, A. F. G.

doi:10.1063/1.1542372

Cited by 11 publications

(4 citation statements)

References 23 publications

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“…The result ( 22) is close to that obtained in [18] which started from the relation between the rates of creation and decay of h-phonons in the l-phonon pulse in the Bose-cone approximation.…”

Section: Thermodynamic Functions Of Anisotropic Phonon Systemsupporting

confidence: 86%

Thermodynamics of anisotropic phonon systems in superfluid helium

Adamenko

Nemchenko

Slipko

et al. 2006

J. Phys.: Condens. Matter

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The thermodynamic functions of anisotropic phonon systems in superfluid helium are calculated for all levels of anisotropy. The results show that the thermodynamic functions of strongly anisotropic phonon systems are essentially different from isotropic ones. It is shown that for strongly anisotropic phonon systems, in thermodynamic equilibrium, the energy density of high-energy phonons, ε/kB≥10 K, is more than ten times higher than in a cone with the same total energy density and with the Bose–Einstein distribution for an isotropic system. The stability curve for anisotropic phonon systems is derived and it is shown that strongly anisotropic phonon systems are thermodynamically stable over a wide temperature range.

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Section: Thermodynamic Functions Of Anisotropic Phonon Systemsupporting

confidence: 86%

Thermodynamics of anisotropic phonon systems in superfluid helium

Adamenko

Nemchenko

Slipko

et al. 2006

J. Phys.: Condens. Matter

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“…In a long pulse, the high-energy phonons do not readily escape and so they form a suprathermal density within the low-energy phonon pulse. 22 For many years, it was thought that 3pp could not happen in liquid 4 He, see, for example, Ref. 23.…”

Section: Introductionmentioning

confidence: 99%

Creation of high-energy phonons in superfluidH4eand the dependence of their angular distribution on heater size

Smith

Wyatt

2010

Phys. Rev. B

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The angular distributions of high-energy phonons, that are created by a short pulse of low-energy phonons propagating in superfluid 4 He, are measured for different heater sizes and heater powers. We find that the intrinsic full width at half height of the high-energy phonons is proportional to the reciprocal of the width of the heater that creates the low-energy phonons. This is similar to the behavior shown by the low-energy phonons where the width of the phonon sheet is inversely proportional to the heater width. We discuss the correspondence between the formation of the phonon sheet by the low-energy phonons and the creation of high-energy phonons, and conclude that the phonon sheet is caused by the creation of high-energy phonons within a few millimeters of the heater. We also show that the total energy in the high-energy phonons increases linearly with heater power, once a threshold power is reached. This indicates that the initial low-energy phonons increase in number but not energy, as the heater power is increased.

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“…The large number of high-energy phonons in a longphonon pulse we call a suprathermal distribution (see Refs. 16,17).…”

Section: Quasiequilibrium Distribution Functions Of Anisotropic Quasimentioning

confidence: 99%

The unusual properties of anisotropic systems of quasiparticles in superfluid He4

Adamenko

Nemchenko

Slipko

et al. 2007

Low Temperature Physics

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We discuss a number of unusual phenomena, which have been discovered recently in anisotropic quasiparticle systems in superfluid 4 He. These include the creation of high-energy phonons by a pulse of low-energy phonons, the suprathermal distribution of high-energy phonons in long phonon pulses, the mesa shape of the angular distribution of low-energy phonons, the creation of a «hot line» when two-phonon pulses cross. The thermodynamic properties of anisotropic quasiparticle systems of He II are derived for all degrees of anisotropy.

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On the suprathermal distribution in an anisotropic phonon system in He II

Cited by 11 publications

References 23 publications

Thermodynamics of anisotropic phonon systems in superfluid helium

Thermodynamics of anisotropic phonon systems in superfluid helium

Creation of high-energy phonons in superfluidH4eand the dependence of their angular distribution on heater size

The unusual properties of anisotropic systems of quasiparticles in superfluid He4

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