The ITER TF coil ripple: Evaluation of ripple attenuation using Fe insert and of ripple enhancement produced by TBM

An accurate evaluation of the toroidal field ripple in ITER has been carried out by finite element models including the presence of the 18 TF coils and a set of ferromagnetic inserts that aim to lower the field ripple well below 1%. As shown, a set of ad hoc distributed plates made of AISI 430 stainless steel (Bsat = μ0Msat ∼1.5 T) and located at the outboard plasma region side in between the vessel shells can reduce the peak ripple at the plasma boundary to ∼0.4% at full toroidal field (i.e., BTF ∼5.3 T at R = 6.2 m). Better compensation can be achieved by adopting higher magnetic saturation materials (e.g., EUROFER). The Test Blanket Modules pair modeled here and made of EUROFER (Bsat ∼1.8 T at 300 K) introduces a large perturbation to the field ripple up to ∼1.1% at full field.