Superconducting magnets, by offering extremely strong magnetic fields, play a key role for high energy physics explorations. However, magnet quenches due to thermal disturbances, significantly suppress magnet performance, and substantially add to the operating cost of superconducting magnets by boiling away huge amounts of extraordinarily expensive liquid helium. Low temperature superconducting can often require dozens of quenches to train the magnet before reaching their design field target. Not to mention that in some cases, an unexpected quench could destroy a millions-of-dollars magnet system. An innovative diagnostic system will be developed in this STTR project to exclude thermal disturbance resources by identifying and localizing magnet defects before magnet cooling, to protect magnet from quench damage by monitoring magnet mechanical structures during magnet operation, and to improve the understanding of magnet training or degradation mechanisms by non-destructive post-operation scanning. The proposed system will utilize laser to generate and sense ultrasound as a non-destructive detection tool to interrogate superconducting magnet to map defect structures within magnets. The proposed laser-ultrasonic imaging technology possesses the advantages of low cost, nonionic nature, and portability over x-ray computed chromograph Developing an industrial laser-ultrasound system specifically for NDT analysis in superconducting magnet is the overall technical goal for this STTR project. In the phase I effort, the feasibility of laser-ultrasound technology for NDT in superconducting magnets will be demonstrated. Considering the time and budget constriction, Phase I work will focus on feasibility demonstration of using laser source to generate ultrasound that meets high energy physics applications, under the guidance of model simulation and the understanding of photoacoustic effect. The development of laser detector is not included because of the exclusively expensive parts and less technical challenge. And it will be integrated in Phase II effort. Another key task of Phase II work is to integrate laser-ultrasound scanning system into superconducting magnet to monitor magnet running at cryogenic temperatures. After completing this project, an advanced laser-ultrasonic system will be available for high energy physics applications, and it will also benefit to medical diagnosis, public transportation, fusion energy, and very high field magnet communities.
