Tsepelin, Viktor and Ahlstrom, Sean and Bradley, Ian and Clovecko, Marcel and Fisher, Shaun and Guénault, Tony and Guise, Edward Ashley and Haley, Richard and Kolosov, Oleg and McClintock, Peter V. E. and Pickett, George and Poole, Malcolm and Woods, Andrew (2014) Frequency-dependent drag from quantum turbulence produced by quartz tuning forks in superfluid He4. Physical review B, 89 (1): 014515. ISSN 1098-0121
PhysRevB.89.014515.pdf - Published Version
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Abstract
We have measured the drag force from quantum turbulence on a series of quartz tuning forks in superfluid helium. The tuning forks were custom made from a 75-μm-thick wafer. They have identical prong widths and prong spacings, but different lengths to give different resonant frequencies. We have used both the fundamental and overtone flexure modes to probe the turbulent drag over a broad range of frequencies f=ω/2π from 6.5 to 300 kHz. Optical measurements show that the velocity profiles of the flexure modes are well described by a cantilever beam model. The critical velocity for the onset of quantum turbulence at low temperatures is measured to be vc≈0.7κω−−−−−√ where κ is the circulation quantum. The drag from quantum turbulence shows a small frequency dependence when plotted against the scaled velocity v/vc