Superfluid Helium in Porous Materials

本文将研究在烧结陶瓷氧化铝粉末上的氦膜 用扭振子技术测量超流体 分数和其他属性。 涡核结构 薄膜将作为温度的函数进行研究，薄膜 厚度和氦三杂质浓度。 第二 实验项目将研究第三和第四声 传播中的氦-四所载的陶瓷材料的非常 低孔隙度。 预测的发散折射率将 在孔隙的逾渗阈值附近进行研究， 陶瓷。 表面折射率也将在 在陶瓷中具有低氦浓度的情况下。

Helium films on sintered ceramic alumina powders will be studied using the torsional oscillator technique to measure superfluid fraction and other properties. Core structure of the vortices in thin films will be studied as a function of temperature, film thickness, and helium-three impurity concentration. A second experimental program will study third and fourth sound propagation in helium-four contained in ceramic materials of very low porosity. The predicted divergent index of refraction will be studied near the percolation threshold for pores in the ceramic. The surface index of refraction will also be studied in situations with low helium concentration in the ceramic.