Перегляд за автором "Wyatt, A.F.G."

Сортувати за: Порядок: Результатів:

  • A new ripplon branch in He II 
    Tanatarov, I.V.; Adamenko, I.N.; Nemchenko, K.E.; Wyatt, A.F.G. (Физика низких температур, 2010)
    We analyse the dispersion relation of ripplons, on the surface of superfluid helium, using the dispersive hydrodynamics approach and find a new ripplon branch. We obtain analytical equation for the dispersion relation and ...
  • Collective modes in superfluid helium when there is a relative velocity between the normal and superfluid components 
    Adamenko, I.N.; Nemchenko, K.E.; Slipko, V.A.; Wyatt, A.F.G. (Физика низких температур, 2008)
    Collective modes are studied in superfluid helium when the normal and superfluid components have a relative velocity w. In this paper the general dispersion relation for first and second sound modes is obtained for ...
  • Creation of high-energy phonons by four-phonon processes in anisotropic phonon systems of He II 
    Adamenko, I.N.; Kitsenko, Yu.A.; Nemchenko, K.E.; Slipko, V.A.; Wyatt, A.F.G. (Физика низких температур, 2007)
    The problem of the creation of high-energy phonons (h-phonons) by a pulse of low-energy phonons (l-phonons) moving from a heater to a detector in superfluid helium, is solved. The rate of h-phonon creation is obtained ...
  • Evolution of a pulse of noninteracting quasiparticles with dispersion and initial angular width 
    Adamenko, I.N.; Nemchenko, K.E.; Slipko, V.A.; Wyatt, A.F.G. (Физика низких температур, 2004)
    The evolution of a pulse of noninteracting quasiparticles, caused by their different velocities and angular distribution of momenta, is studied theoretically. Equations are found that describe the shape of the pulse ...
  • Four and three-phonon scattering in isotropic superfluid helium 
    Adamenko, I.N.; Kitsenko, Yu.A.; Nemchenko, K.E.; Wyatt, A.F.G. (Физика низких температур, 2009)
    We analyse the important role of four-phonon processes (4pp) in isotropic phonon systems of superfluid helium. The matrix elements and the rate of four-phonon processes are calculated. Special consideration is given to the ...
  • Phonons, rotons and ripplons at interfaces 
    Tanatarov, I.V.; Adamenko, I.N.; Nemchenko, K.E.; Wyatt, A.F.G. (Вопросы атомной науки и техники, 2012)
    We use dispersive hydrodynamics to describe thermal excitations of superfluid helium 4. Dispersion relation of the bulk quasiparticles, phonons and rotons, acts as an input parameter of the theory. Wiener and Hopf method ...
  • Relaxation caused by one phonon decay into three in superfluid helium 
    Adamenko, I.N.; Kitsenko, Yu.A.; Nemchenko, K.E.; Slipko, V.A.; Wyatt, A.F.G. (Вопросы атомной науки и техники, 2007)
    The analytical relation for the rate of one phonon decay into three is obtained. Starting from the relation obtained, the rate of spontaneous decay in the first order of perturbation theory is found. It is shown, that ...
  • The theory of kinetic processes in anisotropic phonon systems 
    Adamenko, I.N.; Kitsenko, Y.A.; Nemchenko, K.E.; Wyatt, A.F.G. (Вопросы атомной науки и техники, 2001)
    We present a theoretical investigation of the kinetic properties of strongly anisotropic phonon systems. Such systems can be created in superfluid helium by heat pulses. The general expression for the rates of four-phonon ...
  • The unusual properties of anisotropic systems of quasiparticles in superfluid ⁴He 
    Adamenko, I.N.; Nemchenko, K.E.; Slipko, V.A.; Wyatt, A.F.G. (Физика низких температур, 2007)
    We discuss a number of unusual phenomena, which have been discovered recently in anisotropic quasiparticle systems in superfluid ⁴He. These include the creation of high-energy phonons by a pulse of low-energy phonons, ...
  • Three-phonon relaxation in isotropic and anisotropic phonon systems of liquid helium at different pressures 
    Adamenko, I.N.; Kitsenko, Yu.A.; Nemchenko, K.E.; Slipko, V.A.; Wyatt, A.F.G. (Физика низких температур, 2005)
    Starting from the kinetic equation for phonons in superfluid helium, expressions for the rates of three-phonon scattering in isotropic and anisotropic phonon systems were obtained for different pressures. These expressions ...
  • Некоторые особенности длинноимпульсного режима распространения фононного листа в сверхтекучем ⁴He 
    Вовк, Р.В.; Williams, C.D.H.; Wyatt, A.F.G. (Физика низких температур, 2018)
    Исследовано угловое распределение плотности энергии анизотропного «фононного листа» при его распространении в сверхтекучем ⁴He при длительности импульса до 300 нс. Наличие плоского участка на угловых зависимостях фононного ...
  • Трехфононные взаимодействия и начальный этап эволюции фононного пучка в He II 
    Tucker, M.A.H.; Wyatt, A.F.G.; Адаменко, И.Н.; Жуков, А.В.; Немченко, К.Э (Физика низких температур, 1999)
    Исходя из гидродинамического гамильтониана Ландау получено выражение для характерной частоты трехфононных процессов в сверхтекучем ⁴He, справедливое во всем диапазоне фононных энергий, при которых разрешены трехфононные ...