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Proceedings Paper

Brillouin optical fiber sensor for cryogenic thermometry
Author(s): Luc Thevenaz; Alexandre Fellay; Massimo Facchini; Walter Scandale; Marc Nikles; Philippe A. Robert
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Paper Abstract

Supraconductive installations are now commonly used in large facilities, such as power plants and particle accelerators. This requires a permanent temperature control at very low temperature, but cryogenic temperature measurements in the 1-77K range requires expensive calibrated temperature probes. We report here the possibility to use stimulated Brillouin scattering in optical fibers for temperature sensing down to 1K. Such a technique offers the additional advantage to make possible distributed measurement, so that very large structures and systems can be controlled using a single fiber and a single analyzing instrument. In addition only one by-pass for the fiber is required as input to the cryogenic vessel, that is definitely a key advantage for the design and the energy loss. Brillouin scattering in optical fibers has never been investigated so far at temperature below 77K (nitrogen boiling point). This absence of interest probably results from the constant decrease of scattering efficiency that was observed while cooling the fiber down to 77K. Our measurements show the unexpected feature that scattering efficiency is significantly raised below 50K and is even much better than observed at room temperature. The relevance and the feasibility of the technique is demonstrated in real scale on the supraconductive magnets for the future world largest particle accelerator, namely the large hadron collider (LHC) at CERN Laboratory in Geneva.

Paper Details

Date Published: 27 June 2002
PDF: 6 pages
Proc. SPIE 4694, Smart Structures and Materials 2002: Smart Sensor Technology and Measurement Systems, (27 June 2002); doi: 10.1117/12.472623
Show Author Affiliations
Luc Thevenaz, Swiss Federal Institute of Technology (Switzerland)
Alexandre Fellay, Swiss Federal Institute of Technology (Switzerland)
Massimo Facchini, Swiss Federal Institute of Technology (Switzerland)
Walter Scandale, European Organization for Nuclear Research (Switzerland)
Marc Nikles, Omnisens SA (Switzerland)
Philippe A. Robert, Swiss Federal Institute of Technology (Switzerland)


Published in SPIE Proceedings Vol. 4694:
Smart Structures and Materials 2002: Smart Sensor Technology and Measurement Systems
Daniele Inaudi; Eric Udd, Editor(s)

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