Advances in Fiber Optic Sensors Technology Development for Temperature and Strain Measurements in Superconducting Magnets and Devices

Abstract

The luminosity upgrade of the Large Hadron Collider (HL-LHC) requires the development of a new generation of superconducting magnets based on Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn technology. To monitor the magnet thermo-mechanical behavior during its service life, from the coil fabrication to the magnet operation, reliable sensing systems need to be implemented. In the framework of the FP7 European Project EUCARD, Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn racetrack coils are developed as test beds for the fabrication validation, the cable characterization, and the instrumentation development. Fiber optic sensors (FOS) based on fiber Bragg grating (FBG) technology have been embedded in the coils of the short model coil (SMC) magnet. The FBG sensitivity to both temperature and strain required the development of a solution able to separate the mechanical and temperature effects. This paper presents the feasibility study of the implementation of embedded FBG sensors for the temperature and strain monitoring of the 11-T-type conductor. We aim to monitor and register these effects during the coil fabrication and cool down in a standalone configuration.