Predicting disruption loads within the design cycle for SPARC and ARC using the Open FUSION Toolkit

Eddy currents and associated forces, driven by rapid current quenches during disruptions are important drivers for structural requirements in tokamaks. This talk will present development, validation, and application of ThinCurr¹ and TokaMaker², part of the broader open-source Open FUSION Toolkit³, to the prediction of such currents and their effects within the engineering design cycle for SPARC and ARC. TokaMaker is a time-dependent Grad-Shafranov tool capable of modeling current quenches, Vertical Displacement Events and other relevant events with accurate (2D) vessel geometry, including thick-wall effects, control systems with realistic power supplies, and other relevant features. Currents, forces and other impacts can be directly evaluated or used as input to ThinCurr, a fully 3D thin-wall electromagnetic modeling code, for more accurate simulations and assessment of 3D effects from asymmetries in the vessel and plasma. Use of Hierarchical Off-Diagonal Low-Rank approximation within ThinCurr enables scalability to capture complete devices, including both large (eg. VV) and small (eg. first wall tiles) features in a single model. Both tools utilize unstructured grids that enable tight coupling to design and engineering workflows.

[1] A. Battey et al., NF 64 016010 (2024)

[2] C. Hansen et al., CPC 298 109111 (2017)

[3] https://github.com/hansec/OpenFUSIONToolkit