Equilibrium and stability of ITER configurations with resonant magnetic perturbation

This project is open to Honours, Master and or PhD students and can be scaled accordingly.

The existence of good magnetic flux surfaces is only guaranteed in idealised toroidally axisymmetric configurations. With the loss of symmetry, the field lines can tangle around a fixed-point, creating so-called magnetic islands, or when multiple islands overlap, regions of field line chaos. In ITER, broken toroidal symmetry is introduced deliberately, through the use of resonant magnetic perturbation (RMP) coils, to suppress large explosive instabilities known as edge localised modes (ELMs). It is therefore crucial to evaluate the equilibrium and stability of magnetic field configurations with RMP for ITER scenario.

This project makes use of the Multi-region Relaxed Magnetohydrodynamics (MRxMHD) model and the Stepped Pressure Equilibrium Code (SPEC), co-developed by ANU and Princeton Plasma Physics Laboratory. The baseline axisymmetric magnetic field of ITER will be accessed in the ITER database. The RMP field will be added to the boundary condition of a free-boundary SPEC calculation to obtain a sequence of equilibria with increasing 3D perturbation field and thus size of the islands and chaotic fields. The stability of the system will then be computed from three different ways: The Hessian matrix from SPEC, a dedicated ideal MHD stability code, and a time evolution code such as M3D-C1. A parameter scan will be conducted to understand the effect of 3D perturbation field on plasma waves and stability.