Statement of the problem of situation that is being addressed As commercialized fusion power moves toward realization, there remain many materials challenges which must be solved to ensure long-term and stable operation. For fusion power plants which utilize magnetic confinement, the magnets will have immense amounts of stored magnetic energy. The chance of a large thermal transient disturbing the electromagnet coil winding is non-zero, and when it happens it is necessary to distribute the thermal energy to limit the resulting magnet disturbance. If the disturbance on the coil is not prevented from becoming large, it is then necessary to safely discharge the stored magnetic energy without destroying the electromagnetic coils. The limiting factor to distribute thermal disturbances and safely discharging the electromagnets is the thermal conductivity of the electrical insulation. In addition, when the magnet is turned off for examination or maintenance procedures, it will be important that the materials do not remain radioactively hot for too long. The time needed (for sufficient radiation reduction) is determined by the activation of the materials which are located near the plasma, and if these materials are not selected properly, it may take months for materials to become sufficiently low in radioactivity to be safely handled. General Statement of how this problem is being addressed This proposed project is a collaboration between Hyper Tech Research Inc and The Ohio State University. For this project we will develop two different materials, an ultra-high thermal conductivity electrical insulation and a low activation electromagnetic winding metal stabilizer. The ultra-high thermal conductivity electrical insulation will be an ionic (non-polymeric) solid, and we will solve the difficulty of integrating this material into an electromagnetic winding constructed of rare-earth barium copper oxide (REBCO) high temperature superconducting (HTS) coated conductor. Because REBCO coated conductor has a maximum service temperature of 150 °C, low temperature processing will be required. Low temperature melting and deformable metal-halides will we integrated into the magnet windings followed by a low temperature hot pressing densification. The benefits of this higher thermal conductivity insulation will be demonstrated via cryogenic characterization. Aluminum has been selected by our team to replace copper as metal stabilizer for REBCO coated conductor. Aluminum has lower activation than copper, which may take months to cool-off after radiation exposure and generation of radionuclides. As an added benefit, the electrodeposited aluminum will likely have an even higher cryogenic electrical conductivity than copper and will have a lower mass density. Commercial applications and other benefits Both of these advanced materials will contribute greatly in the development of high power cryogenic electronics. Ultra-high thermal conductivity ceramic electrical insulation can be implemented into non-fusion related high magnetic field cryogenic magnets (MRI, particle beam therapies, high energy physics, nuclear physics), cryogenic motors/generators proposed for future zero net carbon emitting electrified aircraft, and high thermal conductivity electrical standoffs for quantum computing. Aluminum stabilized REBCO would also be used for lightweighting proposed aerospace electrical wiring and interconnection systems, motors/generators, and high energy physics detector magnets.
