Phonon scattering on quantized vortices under quasi-stable laminar flow of superfluid helium

Abstract

Experimental studies of the coefficient of resistance in a quasi-stable laminar flow of superfluid He II under vibrations of a quartz tuning fork immersed in liquid, at a temperature of 140 mK, were performed. After analyzing various additive contributions to the value of the coefficient of resistance, the contribution from the process of ballistic phonon scattering of quantized vortices of superfluid helium at small vibration amplitudes of the prongs was established; this process changes with the increase in amplitudes of these vibrations and the number of quantized vortices. It was shown that the observed experimental dependencies of the resistance coefficient on the fluid flow rate may be explained by multiple phonon scattering, which was not previously considered a dissipation mechanism. The dependence of the effective cross section of the multiple phonon scattering process upon the vibration rates of the prongs of the tuning forks was plotted.