Water Mass Formation, Renewal and Exchange in the Arctic Ocean: Tritium/He, 180 and 14C Measurements on the Arctic 1991 Expedition

这个项目包括一项实验研究，当流量超过一个临界阈值时，超流4He通过微米或亚微米尺寸的孔口时，第一次耗散开始。将测量临界流量的大小及其与温度、压力和孔口形状的关系，以及作为温度函数的起始点的任何统计舍入，以便获得有关所涉及的基本过程的信息，目前尚不存在令人满意的模型。将使用一种小型机械谐振器，能够解决超流体通过孔口振荡流动中的单量子涡旋事件，该孔口是通过电子束光刻和离子束研磨或反应等离子蚀刻制造的。研究将同时使用单孔配置和类似于射频偏置超导量子干涉装置的闭环配置。

This project consists of an experimental study of the first onset of dissipation in the flow of superfluid 4He through an orifice of micron or submicron dimensions as the rate of flow surpasses a critical threshold. Measurements will be made of the magnitude of the critical rate of flow and its dependence on temperature, pressure, and shape of orifice and of any statistical rounding of the onset as a function of temperature, in order to gain information about the fundamental processes involved, for which no satisfactory model now exists. Use will be made of a small mechanical resonator capable of resolving single-quantum-vortex events in the oscillatory flow of superfluid through an orifice that is fabricated by means of electron-beam lithography and ion- beam milling or reactive plasma etching. Studies will be made using both a single-hole configuration and a closed-loop configuration analogous to an rf-biased superconducting quantum interference device.