TY - JOUR

T1 - The damping of a quartz tuning fork in superfluid He-3-B at low temperatures

AU - Bradley, D. I.

AU - Crookston, P.

AU - Fisher, S. N.

AU - Ganshin, A.

AU - Guénault, A.M.

AU - Haley, R. P.

AU - Jackson, M. J.

AU - Pickett, G. R.

AU - Schanen, R.

AU - Tsepelin, V.

PY - 2009/12

Y1 - 2009/12

N2 - We have measured the damping on a quartz tuning fork in the B-phase of superfluid He-3 at low temperatures, below 0.3T (c). We present extensive measurements of the velocity dependence and temperature dependence of the damping force. At the lowest temperatures the damping is dominated by intrinsic dissipation at low velocities. Above some critical velocity an extra temperature independent damping mechanism quickly dominates. At higher temperatures there is additional damping from thermal quasiparticle excitations. The thermal damping mechanism is found to be the same as that for a vibrating wire resonator; Andreev scattering of thermal quasiparticles from the superfluid back-flow leads to a very large damping force. At low velocities the thermal damping force varies linearly with velocity, but tends towards a constant at higher velocities. The thermal damping fits very well to a simple model developed for vibrating wire resonators. This is somewhat surprising, since the quasiparticle trajectories through the superfluid flow around the fork prongs are more complicated due to the relatively high frequency of motion. We also discuss the damping mechanism above the critical velocity and compare the behaviour with other vibrating structures in superfluid He-3-B and in superfluid He-4 at low temperatures. In superfluid He-4 the high velocity response is usually dominated by vortex production (quantum turbulence), however in superfluid He-3 the response may either be dominated by pair-breaking or by vortex production. In both cases the critical velocity in superfluid He-3-B is much smaller and the high velocity drag coefficient is much larger, compared to equivalent measurements in superfluid He-4.

AB - We have measured the damping on a quartz tuning fork in the B-phase of superfluid He-3 at low temperatures, below 0.3T (c). We present extensive measurements of the velocity dependence and temperature dependence of the damping force. At the lowest temperatures the damping is dominated by intrinsic dissipation at low velocities. Above some critical velocity an extra temperature independent damping mechanism quickly dominates. At higher temperatures there is additional damping from thermal quasiparticle excitations. The thermal damping mechanism is found to be the same as that for a vibrating wire resonator; Andreev scattering of thermal quasiparticles from the superfluid back-flow leads to a very large damping force. At low velocities the thermal damping force varies linearly with velocity, but tends towards a constant at higher velocities. The thermal damping fits very well to a simple model developed for vibrating wire resonators. This is somewhat surprising, since the quasiparticle trajectories through the superfluid flow around the fork prongs are more complicated due to the relatively high frequency of motion. We also discuss the damping mechanism above the critical velocity and compare the behaviour with other vibrating structures in superfluid He-3-B and in superfluid He-4 at low temperatures. In superfluid He-4 the high velocity response is usually dominated by vortex production (quantum turbulence), however in superfluid He-3 the response may either be dominated by pair-breaking or by vortex production. In both cases the critical velocity in superfluid He-3-B is much smaller and the high velocity drag coefficient is much larger, compared to equivalent measurements in superfluid He-4.

KW - Superfluid He-3-B

KW - Andreev reflection

KW - Vibrating structures

KW - Critical velocity

KW - QUANTUM TURBULENCE

KW - VIBRATING-WIRE

KW - ANDREEV REFLECTION

KW - ZERO-TEMPERATURE

KW - QUASI-PARTICLES

KW - ORDER-PARAMETER

KW - HELIUM LIQUIDS

KW - TRANSITION

KW - HE-4

KW - LIMIT

UR - http://www.scopus.com/inward/record.url?scp=70449523326&partnerID=8YFLogxK

U2 - 10.1007/s10909-009-9982-z

DO - 10.1007/s10909-009-9982-z

M3 - Journal article

VL - 157

SP - 476

EP - 501

JO - Journal of Low Temperature Physics

JF - Journal of Low Temperature Physics

SN - 0022-2291

IS - 5-6

ER -