The Damping of a Quartz Tuning Fork in Superfluid 3He-B at Low Temperatures
The Damping of a Quartz Tuning Fork in Superfluid 3He-B at Low Temperatures
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DOI：
10.1007/s10909-009-9982-z
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发表时间：
2009-10
影响因子：
2
通讯作者：
D. Bradley;P. Crookston;S. Fisher;A. Ganshin;A. M. Guénault;R. Haley;M. Jackson;G. Pickett;R. Schanen;V. Tsepelin
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文献类型：
--
作者：
D. Bradley;P. Crookston;S. Fisher;A. Ganshin;A. M. Guénault;R. Haley;M. Jackson;G. Pickett;R. Schanen;V. Tsepelin
我们在低于0.3Tc的低温下测量了超流~ 3 He B相石英音叉的阻尼。我们提出了广泛的测量的阻尼力的速度依赖性和温度依赖性。在最低温度下，阻尼由低速下的本征耗散主导。在某个临界速度以上，一个额外的温度无关的阻尼机制很快占主导地位。在较高的温度下，有额外的阻尼从热准粒子激发。的热阻尼机制被发现是相同的振动线谐振器; Andreev散射的热准粒子从超流回流导致一个非常大的阻尼力。在低速下，热阻尼力随速度线性变化，但在较高速度下趋于恒定。的热阻尼非常适合一个简单的模型开发的振动线谐振器。这有点令人惊讶，因为准粒子的轨迹通过超流体流周围的叉尖更复杂，由于相对较高的运动频率。我们还讨论了临界速度以上的阻尼机制，并在低温下与超流3 He-B和超流4 He中的其他振动结构的行为进行了比较。在超流4 He中，高速响应通常由涡旋产生（量子湍流）主导，然而在超流3 He中，响应可能由对断裂或涡旋产生主导。在这两种情况下，超流3 He-B的临界速度要小得多，高速阻力系数要大得多，相比超流4 He的等效测量。
We have measured the damping on a quartz tuning fork in the B-phase of superfluid3He at low temperatures, below 0.3Tc. 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 superfluid3He-B and in superfluid4He at low temperatures. In superfluid4He the high velocity response is usually dominated by vortex production (quantum turbulence), however in superfluid3He the response may either be dominated by pair-breaking or by vortex production. In both cases the critical velocity in superfluid3He-B is much smaller and the high velocity drag coefficient is much larger, compared to equivalent measurements in superfluid4He.