This presentation gives an overview of recent advances in understanding and predicting the macroscopic properties of magnetically confined plasmas, particularly in the absence of continuous symmetries, through new developments in MHD theory and innovations in high-fidelity extended-MHD modelling on leadership-class computing resources, using the M3D-C1 code. We highlight progress toward developing predictive reduced models of nonlinear MHD and their applications to improve design criteria for next-generation, optimised stellarators.
A consequence of the Hamiltonian nature of magnetic field lines, the absence of a continuous symmetry in the toroidal direction can have profound impacts on plasma properties in both tokamaks and stellarators. This makes understanding and predicting nonlinear properties of three-dimensional (3D) MHD important for fusion. Clarifying the role of 3D effects is critical for determining when macroscopic instabilities are benign or have the potential to become disruptive.