Investigation of Superfluid Helium 3

9418665帕卡德首席研究人员将研究与超流氦3有关的两个问题，超流氦3是一种存在于2×10-3K以下的相。第一个研究领域涉及理解当氦3以薄膜的形式存在时其厚度小于超流体相干长度时的性质。主要调查人员将确定，当这些薄膜沉积在覆盖有氦4的衬底上时，是否会表现出过剩的流动性。该计划最初的主旨是开发工具来研究胶片上的表面波，即所谓的第三声。这些波将被用来作为薄膜性能的探针。第二个活动区域将发展氦3直流约瑟夫森结。这些薄弱环节结构应表现出非线性电流压力特性。这些设备可能允许检测宏观量子干扰，类似于在直流超导量子干扰设备中看到的效果。稀有同位素氦3在低于0.002 K的温度下形成超流体状态。首席调查员将确定，随着样品厚度的逐渐减小，这种材料的非常薄的薄膜是否会继续表现出超流体特性。为了回答这个问题，我们将开发能够探测表面厚度波的技术。这些声学技术将提供对薄膜特性的洞察。我们还将研究超流体流经非常小的孔洞时的性质。人们认为，流体通过亚微米小孔时会表现出特殊的行为，这可能会导致非常灵敏的超流体陀螺仪的发展。***

9418665 Packard The Principal Investigators will study two questions related to superfluid helium 3, a phase which exists below 2 x 10-3 K. The first area of research involves understanding the nature of helium 3 when it is in the form of films whose thickness is less than the superfluid coherence length. The Principals Investigators will determine if these films will exhibit superfluidity when deposited on helium 4 covered substrates. The initial thrust of the program is to develop tools to study surface waves on the film, so called third sound. These waves will be used as a probe of the films properties. The second area of activity will develop helium 3 dc Josephson junctions. These weak link structures should exhibit a nonlinear current pressure characteristic. These devices may permit the detection of macroscopic quantum interference analogous to the effects seen in dc superconducting quantum interference devices. % % % The rare isotope helium 3 forms a superfluid state at temperatures below 0.002 K. The Principal Investigators will determine if very thin films of this materials will continue to exhibit superfluid properties as the thickness of the sample is made progressively smaller. To answer this question we will develop techniques capable of detecting surface thickness waves. These acoustical techniques will provide insight into the properties of thin films. The properties of the superfluid when it flows through very small apertures will also be studied. It is believed that the fluid passing through submicron apertures will exhibit peculiar behavior which may lead to the development of very sensitive superfluid gyroscopes. ***