Low Temperature Physics: 37, 551 (2011); https://doi.org/10.1063/1.3626842 (6 pages)
Fizika Nizkikh Temperatur: Volume 37, Number 7 (July 2011), p. 695-702    ( to contents , go back )

Quartz tuning fork oscillations in He II and drag coefficient

I.A. Gritsenko, A.A. Zadorozhko, A.S. Neoneta, V.K. Chagovets, and G.A. Sheshin

B. Verkin Institute for Low Temperature Physics and Engineering National Academy of Sciences of Ukraine 47 Lenin Ave., Kharkiv, 61103, Ukraine
E-mail: gritsenko@ilt.kharkov.ua
pos Анотація:

Received November 10, 2010

Abstract

The temperature dependences of drag coefficient are measured at temperatures ranged from 0.1 to 3.0 K for quartz tuning forks of different size immersed in superfluid He II. It is found that these dependences are similar but the drag coefficients varying value for quartz tuning forks with different geometrical size. It is shown that, if the value of drag coefficient is normalized to the surface area of the moving prong, the specific drag coefficient depends on temperature and oscillation frequency only. The temperature dependences of normalized drag coefficients for tuning quartz forks of different size, wire and sphere are compared. It is shown that in the ballistic regime of quasiparticle scattering these plots are identical and have a slope proportional to T4 , which is determined by the density of thermal excitations. In the hydrodynamic regime at T > 0.5 K the temperature behavior of specific drag coefficient is affected by vibrating body size and oscillation frequency. An empirical relation is proposed to describe the behavior of specific drag coefficient in the whole temperature range at different frequencies for vibrating quartz forks, sphere, and wire.

PACS: 67.10.Jn Transport properties and hydrodynamics;
PACS: 47.37.+q Hydrodynamics aspects of superfluidity, quantum liquids;
PACS: 77.65.Fs Electromechanical resonancequartz resonators.

Key words: quartz tuning forks, drag coefficient, hydrodynamics, ballistics.

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