Magnetohydrodynamic and Electromagnetic Capabilities of the FUSE Integrated-Modeling Framework

FUSE is a flexible framework for integrated whole-facility modeling of fusion pilot plants. We provide an overview of new tools that have been developed to model electromagnetic coils and their interaction with tokamak plasmas through establishing shaped, diverted Grad-Shafranov equilibria, driving ohmic current, and maintaining magnetohydrodynamic (MHD) stability. The VacuumFields code uses a grid-free approach to solve for the flux from a given set of coils and/or to find the optimal coil currents for a desired flux. Two equilibrium solvers have been developed: TEQUILA, a fixed-boundary solver that directly solves for flux-surface shape using an efficient, Miller-extended-harmonic representation, and FRESCO, a free-boundary solver that can be used for rapid shape-control simulations. Current diffusion is modeled by QED, a lightweight, 1D, finite-element code that solves for the time-dependent or steady-state current profile including non-inductive current drive. FUSE can also evaluate a variety of MHD stability metrics. We will show how these tools work together within FUSE to assess vertical stability, to develop steady-state operating points, and to perform time-dependent pulse-design simulations.