Quantum Turbulence in 4He, Oscillating Grids, and Where Do We Go Next?
Quantum Turbulence in 4He, Oscillating Grids, and Where Do We Go Next?
复制标题
4He 中的量子湍流、振荡网格以及我们下一步该何去何从？
DOI：
10.1007/s10909-006-9231-7
复制
发表时间：
2006
影响因子：
2
通讯作者：
L. Skrbek
中科院分区：
文献类型：
--
作者：
D. Charalambous;P. C. Hendry;M. Holmes;G. Ihas;P. McClintock;L. Skrbek
研究了超流4He在低温极限（正常流体密度为零）下量子湍流的实验方法。一个简洁的一般性介绍，包括液体4He，超流性，临界速度开始耗散，量子化涡线和QT。QT可以通过在特征临界速度以上的线或栅格的振荡来机械地创建。有趣的动力学的振荡网格进行了讨论。它表现出增强的有效质量，由于回流，从经典流体力学的预期。结果表明，QT产生的临界速度随温度的升高而升高。像网格或线这样的振荡对象创建的QT在长度尺度方面没有很好的特征，并且QT在空间上不是均匀的。QT可以通过涡核上负离子的捕获来检测。虽然相应的俘获截面尚未测量，但显然非常小，因此不能期望该技术是非常灵敏的。未来，希望通过绘制网格来创建特征良好、同质的QT。正在通过量热技术来寻求提高QT检测的灵敏度，该技术监测由涡线衰变引起的液体温度上升。
Experimental approaches to the study of quantum turbulence (QT) in superfluid 4He in the low temperature limit, where the normal fluid density is effectively zero, are considered. A succinct general introduction covers liquid 4He, superfluidity, critical velocities for the onset of dissipation, quantized vortex lines and QT. The QT can be created mechanically by the oscillation of wires or grids above characteristic critical velocities. The interesting dynamics of the oscillating grid are discussed. It exhibits an enhanced effective mass due to backflow, as expected from classical hydrodynamics. It is found that the critical velocity attributable to the onset of QT production rises with increasing temperature. Oscillating objects like grids or wires create QT that is not well-characterized in terms of length scale, and the QT is not spatially homogeneous. The QT can be detected by the trapping of negative ions on vortex cores. Although the corresponding capture cross-section has not yet been measured, it is evidently very small, so that the technique cannot be expected to be a very sensitive one. In the future it is hoped to create well-characterized, homogeneous QT by means of a drawn grid. Improved sensitivity in the detection of QT is being sought through calorimetric techniques that monitor the temperature rise of the liquid caused by the decay of the vortex lines.