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