Nonlinear phenomena in the vibrations of a quartz tuning fork immersed in superfluid helium
I.A. Gritsenko, T.A. Dubchak, K.A. Mykhailenko, S.S. Sokolov, and G.A. Sheshin
B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Nauky Ave., Kharkiv 61103, Ukraine
Received Jule 12, 2017
Experiments have been carried out on the excitation of hydrodynamic flows in superfluid helium under forced vibrations of a quartz tuning fork immersed in a liquid. Nonlinear oscillations that arise with an in-crease in the driving force are investigated and are manifested by distortion of the shape of the resonant amplitude-frequency characteristic in comparison with Lorentz curves typical for an extremely small force. Nonlinear resonance curves are described using the Duffing equation, the parameters of which are established by comparing the theoretical calculation with the experimental data. Dependence of the velocity of vibrations of the tuning fork legs on the driving force established with the use of the Duffing equation is close to the dependence previously obtained for the quasi-laminar flow of He II and containing a cubic velocity contribution due to the mutual friction caused by scattering of phonons by quantized vortices in a turbulent flow.
PACS: 67.25.dk Vortices and turbulence; PACS: 67.25.dg Transport, hydrodynamics, and superflow; PACS: 67.325.dm Two-fluid model; phenomenology.
Key words: quartz tuning fork, turbulence in liquid he-lium, scattering of phonons by quantized vortices.