权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Experimental study of Quantum Fluids Using a Rotational Cryostat

使用旋转低温恒温器进行量子流体的实验研究

基本信息

批准号：
02405004
负责人：
KUBOTA Minoru
金额：
$ 16万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02405004/
关键词：
Quantum Liquids Thin He films Macroscopic Quantum Phenomena Quantized Vortices Ultralow Temperature Physics rotational Field Vortex Lattice, Vortex Liquids Kosterlitz-Thouless transition 回転クライオスタット 2次元超流動渦対巨視的量子化超低温技術ジョセフソン効果

项目摘要

The present research project aimed to construct a rotatable cryostat for the study of quantum liquids at a few tens of milli Kelvin to kelvin temperatures and plann and perform fundamental experiments using this apparatus. This type of rotating cryostat is built for the first time in Japan and in order to make the project meaningfull the subject to study and the main features of the apparatus had been decided at the begining of the project. Namely the study of superfluidity in He films formed in the well controlled porous glasses has been selected as the main subject. The rotational speed was designed to be controlled from the very low speed of 10-4 rad/sec which is required for the production of a macroscopic circulation corresponding to formation of a single quantum circulation, to rather high speed which is neccesarry to produce as many 'free' quantized vortices as possible.The apparatus is built in the basement room 002 of the A-building of ISSP,a special pit is prepared with a RF … More shield for this apparatus and the rotating structure with high tech air bearing and turning system is built. A diolution cryostat with Joule Thomson precooling stage is home made specially for rotation and tested, in addition another cryostat for stationary test purposes is built and used for preparatory experiment.Although the project demands quite a lot of technical and theoretical preparations without much manpower nor funding, we have achieved the highest smooth rotation speed of 6.2 rad/sec while continuous operation of the cryostat below 100 mK.Currently a precice experiment of tortional oscillator is being prepared under rotation. Which has been performed to study the nature of the superfluidity in thin He films formed in well controlled porous glasses in a steady cryostat where thermal conductivity measurements yealding consistent result with former tortional oscillator experiment.A theoretical study of the nature of superfluidity and phase coherency in He films in porous materials has been being put forth and an interesting feature of pi phase shift across a two dimensional porous weak junction is studied.An experimental study of thin porous glass film production enabled the realistic consideration of the micro bridge out of porous glass with the possible pi phase shift. Less

本研究项目旨在构建一个可旋转的低温恒温器，用于研究几十毫开尔文到开尔文温度下的量子液体，并计划使用该装置进行基础实验。这种类型的旋转低温恒温器在日本是第一次建造，为了使该项目有意义，在项目开始时就确定了研究主题和设备的主要特征。即选择在可控多孔玻璃中形成的He膜的超流性研究作为主要课题。旋转速度被设计成从产生对应于形成单个量子循环的宏观循环所需的10-4弧度/秒的非常低的速度控制到产生尽可能多的“自由”量子化涡旋所需的相当高的速度。该装置被建造在ISSP的A楼的地下室002中，用RF制备专用凹坑， ...更多信息为该装置和旋转结构建造了屏蔽罩，并采用高技术的空气轴承和旋转系统。自制了一台旋转用的焦耳-汤姆逊预冷级扩散恒温器并进行了试验，另外还建造了一台静止试验用的低温恒温器并进行了预备性试验，虽然该项目需要大量的技术和理论准备，但没有太多的人力和经费，在100 mK以下连续工作时，获得了6.2rad/sec的最高平稳转速。目前，扭转振荡器的精密旋转实验正在准备中。在稳态低温恒温器中，研究了在多孔玻璃中形成的He薄膜的超流性，热导率的测量结果与以前的扭振实验结果一致。对多孔材料中He薄膜的超流性和相相干性进行了理论研究，并在二维多孔玻璃中发现了π相移的有趣特征。薄多孔玻璃膜生产的实验研究使得能够现实地考虑多孔玻璃中的微桥与可能的π相移。少