Materials World Network: A Collaborative Experimental Investigation of Pure Quantum Turbulence in Superfluid 4He at Very Low Temperatures

材料世界网络：极低温超流体 4He 中纯量子湍流的合作实验研究

• 批准号: 0602778
• 负责人: Gary Ihas
• 金额: --
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0602778&HistoricalAwards=false
• 关键词: Materials; World; Network; Collaborative; Experimental

Turbulence in classical fluids is important and challenging both for theory and for many practical applications. This research aims to understand how classical turbulence is modified in a superfluid, inwhich flow is severely restricted by quantum conditions associated with the quantization of angular momentum and a complete lack of viscosity.At higher temperatures, superfluids exhibit "two-fluid" behavior, a normal fluid coexisting with the superfluid component in which the quantum effects are important. There is already strong evidence that at these temperatures turbulent structures on large length scales can be very similar to their classical counterparts, although dissipative processes acting on small scales are very different. It is suspectedthat a similar situation exists at very low temperatures, where the normal fluid is absent, and where simple mechanisms for the decay of the turbulence have disappeared. Our program seeks to provide experimental evidence relating to these low temperatures, at which the fundamental behavior of very pure forms of quantum turbulence ought to be observable, the turbulence being generated by either a steadily moving grid or an oscillating grid. The mechanical behavior of the oscillating grid will provide evidence about the nucleation of turbulence, and calorimetric observations with the towed grid will measure turbulent decay, which reflects not only dissipation on small scales but also the overall turbulent structure. Quantum turbulence is of great intrinsic interest, and its study could lead to a better understanding of classical turbulence.Success of the proposed experiments is dependent on the development of close interactive collaboration between Florida, Birmingham, Lancaster and Kiev. The Lancaster experimental group will do the vibrating grid work, and the Birmingham Co-Investigator will support theory development. The Kiev group will use its full chip fabrication line to develop micro-size thermal and pressure sensors for the work. Studentsand postdoctoral associates from all labs will work in the other labs to both promote the overall effort and to further develop each researcher's capability.

经典流体的湍流对于理论和许多实际应用都很重要，而且具有挑战性。这项研究旨在了解如何在超流体中修改经典的湍流，而流动严重限制了与角动量量化和完全缺乏粘度相关的量子条件。在较高的温度下，超氟在较高的温度下表现出“两氟”的行为，是一种正常的流动性，一种与超氟化的成分相共渗透，这是量子效应的超氟化，这是量子效应的重要性。 已经有强有力的证据表明，在这些温度下，大长度尺度上的湍流结构可能与它们的经典同行非常相似，尽管作用在小尺度上的耗散过程大不相同。怀疑在不存在正常液体的温度下存在类似情况，而湍流衰减的简单机制消失了。我们的计划试图提供与这些低温有关的实验证据，在这种证据上，应该可以观察到非常纯净的量子湍流形式的基本行为，这是由稳定移动的网格或振动网格产生的湍流。振荡网格的机械行为将提供有关湍流成核的证据，而用牵引网格的量热观测将测量湍流的衰减，这不仅反映了小尺度上的耗散，还反映了整体湍流结构。量子湍流具有很大的内在兴趣，其研究可能会更好地理解经典的湍流。拟议的实验的核心取决于佛罗里达州，伯明翰，兰开斯特和基辅之间紧密互动协作的发展。兰开斯特实​​验组将进行振动的网格工作，伯明翰共同投资者将支持理论发展。基辅组将使用其完整的芯片制造线来为工作开发微型热和压力传感器。 来自所有实验室的学生和博士后同伴将在其他实验室工作，既可以促进整体努力，又要进一步发展每个研究人员的能力。