High-temperature superconducting cables for compact fusion reactors

The feasibility of fusion as a practical energy source needs to be improved significantly by removing some of the restrictions that low-temperature superconductors put on the fusion magnet systems. One method to simplify the magnet system is by using high-temperature superconductors that allow for more compact magnet systems with higher performance and much larger temperature margins. The compact, high-field magnet systems require high- current, flexible cables wound from high-temperature superconductors that are highly transposed to enable low-loss field ramping and a safer magnet operation. There are currently no highly transposed, flexible magnet cables that would enable compact, high-field fusion machines. This proposal seeks to develop low-loss, flexible, high-current magnet cables wound from high-temperature superconductors, allowing development of compact, high-field fusion magnets. During Phase I, we will develop and test the strands from which the high-current fusion cable will be wound. Initial designs of a fusion magnet cables able to carry 50-100 kA of current in a field of 20 T will be developed. Sub-scale magnet cables will be constructed and their performance will be evaluated. During Phase II we will manufacture full-size magnet cables for compact fusion magnets and test their electrical and mechanical performance at the rated current and optimize their layout to ensure their performance doesn’t degrade during operation. Reliable, low-loss, flexible high-temperature superconducting magnet cables will enable compact fusion magnets that operate at high fields. Flexible, low-loss magnet cables will directly benefit other applications, such as high-field scientific and detector magnets.