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 highcurrent, flexible cables wound from high-temperature superconductors that are highly transposed to enable low-loss field ramping and 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 hightemperature superconductors, allowing development of compact, high-field fusion magnets. During Phase I, we’ve demonstrated the clear feasibility of developing highly transposed multi strand cables wound from CORC® wires that would carry 50 – 100 kA in a field of 20 T. We’ve demonstrated the ability to operate the cable without any significant degradation due to mechanical stresses, even after 100,000 stress cycles, and during bending to 1 meter diameter. During Phase II we will manufacture full-size magnet cables for compact fusion magnets and demonstrate their performance at 80 kA in a 10.8 T background field. If successful, the program will result in high-quality cables for compact fusion magnets that are highly transposed to allow low-loss field ramping, safe operation even during magnet quench, with no performance degradation. These cables would enable a rapid development of compact fusion magnets.Commercial Applications and Other Benefits Reliable, low-loss, flexible high-temperature superconducting magnet cables will enable compact fusion magnets that operate at high fields. These cables will directly benefit other applications, such as high-field scientific and detector magnets.