Speaker
Description
At Tokamak Energy (TE) we have been working on a range of technology blocks and magnet demonstrators to raise the Technical Readiness Level (TRL) of REBCO HTS based magnets for spherical tokamaks (ST). This is a broad programme addressing technologies including coil manufacturing, quench protection, modelling and simulation, HTS irradiation, and other aspects. This talk will demonstrate how our current active development programmes are derisking our journey to delivery of the HTS coil systems for fusion pilot plants, with particular focus on coil manufacturing.
The Demo4 demonstrator, consisting of 44 HTS coils in 14 Toroidal Field (TF) limbs and 2 Poloidal Field (PF) stacks, will demonstrate the function of the coils at temperatures and in background field environments that closely replicates how larger scale coils would function in a commercial scale ST. Operation of Demo4 will give detailed validation of the predicted operational margins of the 44 coils in steady state, transient scenarios and system fault conditions. It will also provide evidence on the optimal deployment of HTS in larger magnet systems, potentially saving millions of dollars in coil costs. For example, how much grading can be applied to large scale TF coil return limbs?
To optimise the use of REBCO in the coils and provide the engineering current density the ST requires, the TF coil designs are based on stacked tape cables. Instead of forming tapes into steel clad cables and using large scale machines to bend these stiff cables into coils, we are developing tooling to wind coils directly into copper structures to form compact coil packs with high thermal conductivity and enough thermal mass to absorb the magnetic energy in a fault condition without inducing damaging thermal stresses in the structures. The winding machine is coil size and shape agnostic. These coil packs can then be mounted in a steel support structures to contain the stresses associated with magnet operation.
