Vortex dynamics in quantum and classical fluids

****非技术摘要****在极低的温度下，液氦由于量子力学效应而成为具有不寻常特性和零粘度的超流体。超流体的一个不寻常的方面是量子涡旋的存在，一种量子力学龙卷风，它构成了超流体氦流的支柱。 该奖项支持一个使用独特技术来观察量子涡旋的形成和运动的项目。该项目将探索的大多数现象以前从未见过，包括涡环的运动和涡旋的交叉，这会在它们接触时引起剧烈的折断。本科生和研究生是该项目的核心，因为他们学习许多新技术并为科学职业做好准备。除了更好地理解超流体与普通流体的不同之外，这项研究还满足了相关系统中科学发现的异常广泛的需求，涉及金属变形、太阳磁场、旋转流的地球物理学以及涉及希格斯场的高能理论。 **** 技术摘要 **** 该奖项支持一个研究和表征超流氦中量子化涡旋的形成和动力学的项目。 这些研究将利用一种独特的能力来可视化微米级的氢粒子，这些粒子可以被涡流捕获。 研究重点是涡旋重联、涡环、热逆流、旋转流和量子湍流。此外，该项目将探索量子湍流和经典湍流之间的异同，以便更好地理解两者。超流氦中的量子化涡旋可以作为许多其他系统的模型，因此该项目不仅有可能影响凝聚态物理中的许多子领域，而且还可能影响天体物理学、太阳物理学、旋转流地球物理学以及涉及希格斯场的高能理论。该项目通过本科生和研究生研究人员的参与和培训以及公共宣传活动扩大了其影响力。

****NON-TECHNICAL ABSTRACT****At very low temperatures, liquid helium becomes a superfluid with unusual properties and zero viscosity owing to quantum mechanical effects. One unusual aspect of superfluids is the existence of quantum vortices, sort of quantum mechanical tornadoes, that form the backbone of superfluid helium flow. This award supports a project using a unique technique to observe the formation and motion of the quantum vortices. Most of the phenomena the project will explore have not been seen before and include the motion of vortex rings and the crossing of the vortices which causes a violent snapping at the point when they touch. Undergraduate and graduate students form the heart of the project as they learn many new techniques and prepare for scientific careers. Beyond a better understanding of how superfluidity is different from normal fluids, the research serves an unusually broad need for scientific discovery in related systems involving deformation of metals, solar magnetic fields, geophysics of rotating flows, and high energy theory involving the Higgs field. **** TECHNICAL ABSTRACT **** This award supports a project to investigate and characterize the formation and dynamics of quantized vortices in superfluid helium. These studies will use a unique capability to visualize micron-sized hydrogen particles, which can be trapped by the vortices. The research focuses on studying vortex reconnection, vortex rings, thermal counterflows, rotating flows, and quantum turbulence. Furthermore, the project will explore the similarities and differences between quantum and classical turbulence in order to better understand both. Quantized vortices in superfluid helium serve as a model for a number of other systems, such that this project has the possibility to impact not only a number of sub-fields in condensed matter physics, but also astrophysics, solar physics, the geophysics of rotating flows, and high energy theory involving the Higgs field. The project broadens its impact through the involvement and training of undergraduate and graduate researchers, and through public outreach activities.