Realization of the Lambda Transition Temperature of 4He Using Sealed Cells

This paper presents lambda-point measurements obtained at CL, IMGC, and NPL in the past two years using sealed cells made at CL. The cells consist of two chambers containing liquid helium, separated by a stainless-steel capillary. When the He I/He II interface is located in the capillary, the large...

Full description

Saved in:
Bibliographic Details
Published in:Temperature: Its Measurement and Control in Science and Industry; Volume 7, Part 1 Part 1, 2003-01, Vol.684, p.191-196
Main Authors: Lin, Peng, Mao, Yuzhu, Hong, Chaosheng, Pavese, Franco, Peroni, Ilaria, Head, David, Rusby, Richard
Format: Article
Language:English
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:This paper presents lambda-point measurements obtained at CL, IMGC, and NPL in the past two years using sealed cells made at CL. The cells consist of two chambers containing liquid helium, separated by a stainless-steel capillary. When the He I/He II interface is located in the capillary, the large thermal conductivity of He II ensures that the lambda temperature T is established in the top chamber. Heat flows change the position of the interface, but have only a small effect on the temperature of the top chamber. Because of the self-adjusting effect of the He I column within the capillary, the lambda transition temperature plateau was recorded in the top chamber for many hours with a fluctuation of 3.2 muK. The temperature of the lambda transition at zero heat flow is determined by measuring the temperature at several heat flows and extrapolating to zero. The best realizations of T were made at NPL with a standard deviation of 5.8 muK, and the effect of the finite conductivity of He II was observed for the first time in this cell.
ISSN:0094-243X
DOI:10.1063/1.1627123