Scattering of phonons on quantized vortices under a quasi-stable laminar flow regime of superfluid helium
I.А. Grytsenko, Т.А. Dubchak, К.А. Mikhailenko, S.S. Sokolov, and G.А. 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 February 18, 2018
Experimental studies are carried out of the resistance coefficient in a quasi-stable laminar flow of superfluid He II under vibrations of a quartz tuning fork immersed in a liquid at a temperature of 140 mK. As a result of the analysis of various additive contributions to the value of the resistance coefficient, a contribution is established from the process of ballistic phonon scattering on quantized vortices of superfluid helium at small oscillation amplitudes of the tuning fork legs, which, with an increase in the amplitude of these oscillations and the number of quantized vortices, is replaced by a new process. It is shown that the observed experimental dependences of the resistance coefficient on the fluid flow velocity can be explained if this process consists in multiple phonon scattering, which was not previously proposed as a dissipation mechanism. The dependence of the effective cross section of the multiple scattering process on the velocity of oscillation of the tuning fork legs is constructed.
PACS: 67.25.dk Vortices and turbulence;
Key words: quartz tuning fork, turbulence in liquid helium, scattering of phonons by quantized vortices.
Published online: June 27, 2018