Multi-Purpose Fiber Optic Sensors for HTS Magnets

Magnets using new high temperature superconductor (HTS) materials are showing great promise for high magnetic field applications such as particle accelerators and the plasma-confinement systems for fusion reactors. However, the development and operation of these magnets is limited because appropriate sensors and diagnostic systems are not yet available to monitor the manufacturing and operational processes that dictate success. Such real-time measurements would aid the development of high-field magnets that are subject to large Lorentz forces and would allow the effective detection of quenches, so that the stored energy of operating magnets can be extracted and/or dissipated without damaging the magnet. In this project, optical fibers will be imbedded within the HTS magnets to monitor strain, temperature, and irradiation, and to detect quenches. In the case of Bi2212, the fiber will be used as a monitor for heat-treatment processes to ensure that the entire magnet has reached thermal equilibrium. In Phase I, fiber optic materials will be evaluated for compatibility with HTS magnets, including their physical behavior at high temperature in oxygen, in order to determine their compatibility with Bi2212 processing. Techniques for imbedding the fibers in coil packages will be investigated, and their effectiveness for process monitoring and quench detection will be determined. Commercial Applications and other Benefits as described by the awardee: Magnets constructed from HTS would benefit from sensitive diagnostics to monitor strain and temperature, both for magnet development and day-to-day operation. The sensors to be developed will facilitate HTS magnets for many scientific, medical, military and power applications.