Stable, Low-Loss Joints for HTS Fusion Magnets

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 (HTS) that allow for a higher magnet performance and much larger temperature margins.Successful application of HTS in fusion magnets requires reliable HTS cables and low-resistance cable joints.This proposal seeks to develop high-current CORC® cables with reliable, low-resistance joints between that would allow for practical fusion magnets to become a reality.Joints between magnet cables, capable of carrying currents exceeding 80 kA, will be developed into an industrial product in collaboration with three large entities developing HTS fusion machines.During the Phase I and Phase II programs, high-current HTS CORC® cables and joints were successfully developed and tested at 4.2 K in fields up to 11 T.The success of the initial development attracted three major entities, each developing a fusion machine that requires HTS conductors.During the Phase IIB program, we will work with Lockheed Martin Aeronautics, the Princeton Plasma Physics Laboratory and the United Kingdom Atomic Energy Authority to test CORC® conductors and demountable joints at elevated temperatures between 20 – 40 K and optimize their performance for some of the HTS magnets in each of the three fusion machines.By teaming up with our end users, the program will likely result in a high level of confidence in our technology, a reduced risk to the design of the fusion machines, and a high likelihood of a significant commercial market for CORC® technology.Reliable HTS cables and low-resistance joints between them will enable compact fusion magnets, high-field magnets for scientific experiments and the next generation of accelerator magnets for particle physics and proton cancer treatment facilities.They will also enable highdensity power transmission cables for Department of Defense applications.