Long term experience with the “industrial” 3He vapour-pressure thermometer

V Benda,T Vafeiadis

doi:10.1088/1757-899x/171/1/012124

Abstract

On the basis of very good experience with a prototype of a 3He vapour-pressure thermometer installed in the magnet feed box (MFB – prototype of LHC magnet test bench), an upgraded version of this thermometer was developed with emphasis on the improvement of its long term stability, reliability and “series” production. The thermometer is working typically around 1.9 K. This article summarises the key points of the prototype design, its upgrade leading to the “industrial/series” realization, the long term experience and the calibration crosscheck of these thermometers after 15 years of operation.

Highlights

During tests of LHC prototype magnets on Magnet Feed Box (MFB) a temperature shift, with respect to the lambda point, of electro-resistive thermometers was observed
On the basis of the good experience with the first 3He thermometer installed in the MFB it was decided to develop a more “industrial” version of this thermometer and to install it in all the 12 serial Cryogenic Feed Boxes (CFB) which are part of the magnet test facility built to test the LHC dipole and quadruple superconducting (SC) magnets
After successful tests of this prototype including a calibration in the CERN cryogenic laboratory, it was installed in 1995 in the MFB

Summary

Introduction

During tests of LHC prototype magnets on Magnet Feed Box (MFB) a temperature shift, with respect to the lambda point, of electro-resistive thermometers was observed. As the 3He bulb is considered as a temperature standard it was not used as a calibration, but rather as a comparison to the other thermometers to avoid any mistakes in its design Another crosscheck was done directly on the MFB during the magnet test thanks to an enormous peak of 4LHe heat capacity at lambda point. All these measurements confirmed the good precision of this thermometer. In 2001 the MFB was refurbished in order to build the CAST [4] experiment at CERN This 3He test bulb thermometer has been running with some breaks till today.

Results of the measurements in CAST experiment at CERN

Serial Product

Conclusion