Distributed, Real-Time Fiber-Optic Sensing System for Superconducting Magnets

Fiber optic-based sensing devices and systems allow for electromagnetic interference-immune interrogation of temperature and strain distribution within the cryomodule coil winding pack of superconducting magnets. A specific use of fiber sensors is for rapid and redundant quench detection. Novel fiber-optic sensors may also be used for precision measurement of distributed and local temperature and/or strain for diagnostic and scientific studies of conductor behavior and code calibration. IFOS’ innovation in Phase I is a novel, highly multiplexed, dense fiber-optic sensor array based on the use of a fiber Bragg grating (FBG) for temperature and strain monitoring within the coil winding pack of superconducting magnets. The proposed system is first of its kind in terms of its capability of monitoring dense FBG arrays on a single fiber or multiple fibers, providing an FBG- based sensing system with an order of magnitude improved performance in terms of number of sensors, measurement precision, and interrogation speed. The technical innovation that IFOS will use to achieve the above functionality includes an optical network that uses Multi-Band Dense Wavelength Division Multiplexing (MB-DWDM) to monitor dense sensor arrays. Using this approach, it will be possible to achieve, for example, 1024 sensors simultaneously sampled at 500 samples per second). Hardware ruggedness, simplicity of operation and robust software with built-in intelligence are key features of the prototype to be developed in Phase II. In Phase II the IFOS research team will develop the complete system prototype and demonstrate its cost- effective, reliable and accurate operation. Fiber-optic sensors installed in superconducting magnets provide capability for temperature monitoring of magnets during heat treatment and during operation for quench detection and rectification, strain monitoring during cool-down and operation to ensure acceptable levels are maintained to predict magnet lifetime and to allow lifetime optimization by measuring and managing the heat and strain distribution within the magnet. The successful development and application demonstration of the proposed sensing system will be valuable to the development of superconducting magnets for fusion energy systems with potential for significant impact.