Superfluid Helium and Porous Materials

利用扭转振荡器和声学技术，研究了4He薄膜吸附在滑铸Al2O3粉末上的超流体转变。涡芯尺寸是温度、膜厚和3He浓度的函数。转换时的耗散将在1 kHz至30 MHz的频率范围内测量。并提出了多孔陶瓷弯曲度的测量方法；并利用涡环理论研究了跃迁的动力学。测量多孔基板上液态4He薄膜的超流体密度可以为研究低温下凝聚态物质的量子行为提供新的见解。

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.