Superfluid Helium and Porous Materials

4 He膜吸附在滑移面上的超流相变研究 将使用扭转振荡器制备铸造Al 2 O3粉末， 声学技术 涡核尺寸将作为 温度、膜厚和3 He浓度的函数。 的 转换时的耗散将在一个频率范围内测量 范围从1 kHz到30 MHz。 还建议测量 多孔陶瓷的弯曲度;并研究 用涡环理论研究了λ跃迁。 用原子力显微镜测量液态~ 4 He膜中的超流密度 多孔衬底可以提供新的洞察量子行为 在非常低的温度下凝聚的物质。

A study of the superfluid transition of 4He films adsorbed on slip- cast Al2O3 powder will be made, using a torsion oscillator and acoustic techniques. The vortex core size will be obtained as a function of temperature, film thickness and 3He concentration. The dissipation at the transition will be measured over a frequency range from 1 kHz to 30 MHz. It is also proposed to measure the tortuosity of porous ceramics; and to study the dynamics of the lambda transition using a vortex-ring theory. Measurement of the superfluid density in liquid 4He films on a porous substrate can furnish new insight into the quantum behavior of condensed matter at very low temperature.