Magnetic field lines tracing for ITER ELM control coils

For the mitigation of high, transient heat and particle fluxes caused by Edge Localized Modes (ELMs), magnetic perturbation coils are planed at the next step fusion experiment ITER. These coils generate an external magnetic perturbation field with a resonant alignment to the field line pitch angle in the plasma edge, breaking the axissymmetry of the tokamak. In this contribution, a detailed study of the new three-dimensional magnetic boundary, computed from vacuum field line tracing, is shown. Analysis of the perturbed system with Poincare plots and modeling of the field line connection length shows that a system evolves which is very similar to the stochastic boundary applied at the DIII-D tokamak for complete ELM suppression. The open field line region intersects the divertor target in ITER in a helical pattern which will determine a non-axissymmetric heat and particle fluxes. The magnetic footprint geometry is presented for a standard, inductive plasma setup as well as for a high magnetic shear, steady state scenario and discussed with particular reference to recent ITER divertor design reviews.