Fiber Bragg Grating sensors based monitoring system for superconducting accelerator magnets

Abstract

New generation of accelerator magnets for high energy applications currently designed, manufactured and tested at the European Organization for Nuclear Research (CERN) require the implementation of precise cryogenic sensors with long-term robustness and reliability able to withstand cryogenic temperature and to monitor the mechanical stresses affecting the winding during all the stages of his service life, assembly, cool down and powering. Monitoring the mechanical behavior of the magnet from assembly to operation is a critical task which aims to assure the integrity of the magnet and to safely handle the coils made of new brittle material. This contribution deals with the first successful embedding of Fiber Bragg Grating sensors in a subscale Nb 3 Sn dipole magnet in order to monitor the strain developed in the coil during the cool down to 1.9 K, the powering up to 15.8 kA and the warm up, offering new perspectives for the development of a complementary sensing technology based on fiber optic sensors.

Self-monitoring ‘SMART’ (RE)Ba2Cu3O7−xconductor via integrated optical fibers

“…Therefore, the sensing capability is confined to the predetermined grating location and if a change in strain or temperature occurs elsewhere, it is not detected. Although the use of FBG sensors for superconductor magnets monitoring has been advanced [30][31][32][33][34][35], the spatial resolution will always be strongly limited and, thus, the advantages over voltage measurements reduce drastically.…”