Distributed Magnetic Field and Temperature Monitoring for Linear Superconducting Radio Frequency Cavities

Recent advances in surface engineering by doping and annealing led to an unprecedented quality factor, however the process is vulnerable to residual flux trapping when the cavity transitions to superconducting state during cooldown. As more efficient, lower cost particle accelerators are desired, significant research and development efforts are being devoted in recent years to understanding the mechanisms of flux trapping, their contribution to the RF losses, and methods to reduce the amount of trapped flux and diagnostic tools are need to map the temperature and magnetic fields. The overall objective of the proposed Phase I program is to design, construct and demonstrate a fiber optic sensing system capable of cryogenic temperature and magnetic field measurements that can be readily deployed and seamlessly integrated with monitoring of superconducting radio frequency cavities and superconducting magnets. This one-of-its-kind monitoring system will leverage a commercially available sensor interrogator and a unique multi-material optical fiber developed under previous federally funded programs to deliver performance that cannot currently be achieved with any other technology. In this Phase I effort, Sentek and VT will (1) engage in active dialogue with the research team at U.S. Department of Energyĺs Thomas Jefferson National Accelerator Facility to assure the sensing system is fit-for-use and provides the most benefit, (2) design and construct the magnetic and temperature monitoring system to meet the performance and operating requirements set forth by DOE, and (3) complete performance testing of a prototype system in the simulated environmental testing facilities at Virginia Tech. Upon completion of this 9-month effort, the technology will be well-positioned for on-site deployment and operation in the Phase II program. A fiber optic sensing fiber capable of distributed temperature and magnetic field measurements with high spatial resolution over long distances will find immediate commercial applications in the monitoring of superconducting radio frequency cavities and superconducting magnets. The proposed technology is truly unique and will provide benefit to the renewable energy sector, as a whole, for monitoring critical electrical power generation and distribution assets and for monitoring and securing critical infrastructure via real-time object detection and structural health monitoring.