High Temperature Superconducting Magnets for Compact Modular Fusion

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Tokamak Energy (TE) has unlocked a potential new route to scalable fusion power that is cost-effective and does not require huge infrastructure and capital expenditure. The technology will revolutionise world energy production -- it will be possible to produce more energy, more cheaply and with fewer undesirable consequences than existing technologies (e.g. by eliminating long term nuclear waste and dramatically reducing carbon emissions while not requiring huge tracts of land).The TE route to fusion power harnesses two specific technologies -- spherical tokamaks and high temperature superconducting (HTS) magnets. The company currently has a world leading position in HTS magnets with 19 families of patents already filed, but wishes to accelerate its development programme, particularly given new competition from an MIT spin-out, funded by $50M from Italian oil company, ENI.Our vision is that this project will deliver rapid progress in a key area of HTS magnet development to keep us ahead of the competition and allow us to raise substantially more private investment over the next 5 years.The key objective is to design and develop novel HTS magnets with particular features crucial for certain magnetic coils on tokamaks. These features, especially the ability to alter the magnetic field on a timescale of 1 to 10 seconds, will mean that the magnet technology is also suitable for other applications such as medical instruments and energy efficiency/storage.The main area of focus is poloidal field (PF) HTS magnet coils. When the current in the coil changes, eg during initial energisation or adjustments to control the plasma, energy is dissipated, warming the coil. If the current sweep rate is too fast, the superconductor can become resistive, warming the coil more quickly. In extremis, the coil can go into thermal runaway, or "quench". These "AC loss" effects can be minimised by changes to the cable design and construction. The necessary PF coil current sweep rates are up to three orders of magnitude faster than required for the main toroidal field (TF) magnet coils.To meet these requirements the PF coils need an innovative cable construction and a different quench protection approach. We have several candidate solutions to this technology challenge and a suitable cryogenic test-rig to enable rapid tests of prototypes. We expect to be able to file new patent applications as a result of this project. During the project we will evaluate the best way forward with the other magnet applications.