Multi-purpose fiber optic sensors for high temperature superconducting magnets

Abstract

Tokamak fusion reactors require the development of magnets capable of generating large magnetic fields under stringent structural constraints. Magnets made with high temperature superconductors (HTS) are well suited to this application, but are vulnerable to quench occurrence during operation. Temperature and strain sensors based on fiber optics are being developed as a first step to counter this contingency. Optical fibers with Bragg gratings are amenable to embedding within superconducting magnets to monitor temperature, strain, irradiation, and to detect quench occurrence. Additionally, in the case of AgX/Ag/Bi2Sr2CaCu2Ox, (Bi2212) wire magnets, fiber optics can serve as a heat treatment process monitor for wind-and-react (W&R) manufacturing. Here we show that it is possible to detect quenches using fiber Bragg grating sensors and examine the effects of Bi2212/optical fiber co-sintering on Bi2212 performance and fiber survivability.