Viscosity measurements of helium-4 using vibrating wire as a viscometer

Semicircular vibrating wire viscometer was constructed using a niobium wire (diam. 47 μm) to be used for liquid helium viscosity measurements. The wire was driven by an AC current under a constant magnetic field. The Lorentz force acting on the wire caused it to vibrate. Voltage was induced across the wire due to the changing magnetic flux. The AC current source was swept through the resonance frequency of the vibrating wire while recording the induced voltage. Viscosity values can be extracted from the linewidth of the resonance peak. In this work, initial tests using the viscometer are reported. The viscosity values could not be extracted from the experiments yet. Instead, the experimental data is compared with the theory in order to identify the possible sources of damping.