CERN Accelerating science

Article
Title Monitoring of a high temperature superconducting magnet by means of distributed optical fiber sensing
Author(s) Marcon, Leonardo (U. Padua (main) ; Unlisted, CH) ; Castaldo, Bernardo (CERN) ; Chiuchiolo, Antonella (CERN ; INFN, Salerno) ; Van Nugteren, Jeroen (CERN ; Unlisted, CH) ; Bajas, Hugues (CERN) ; Kirby, Glyn (CERN) ; Galtarossa, Andrea (U. Padua (main)) ; Bajko, Marta (CERN) ; Palmieri, Luca (U. Padua (main))
Publication 2025
Number of pages 8
In: Opt. Laser Technol. 192 (2025) 113767
DOI 10.1016/j.optlastec.2025.113767 (publication)
Subject category Detectors and Experimental Techniques
Abstract Distributed optical fiber sensor is a unique technology that offers unprecedented advantages and performance especially in those experimental fields where the environmental harshness limits the applicability of standard sensors. By measuring the faint light backscattered by the fiber in response to a well-tailored probing signal, distributed sensors allow mapping the variation of physical parameters along the fiber path with high spatial resolution. In this work we report on the application of this technology to the monitoring of a complete mockup prototype of high-temperature superconducting magnet, developed for the future High Luminosity Large Hadron Collider at CERN. Four optical fibers have been embedded in different areas of the magnet and have been measured by optical frequency-domain reflectometry. The magnet was first monitored during the cooling phase from room temperature down to 4.5 K; results show that, despite the huge temperature variation, the structure reacts uniformly, without suffering from localized thermal stress, confirming the design targets. In a second phase, the magnet was monitored while it was powered with electric currents up to 2.5 kA, at the operational temperature of 50 K. In this case results show non-negligible localized strain accumulations due to the Lorentz forces, which are marginally higher than what was expected by design. The experiment confirms the unique advantages that distributed optical fiber sensors offer to both the design and operation control of structures as critical and complex as superconducting magnets.
Copyright/License publication: © 2025 The Authors (License: CC BY-NC-ND 4.0)

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