A novel approach for solving three dimensional eddy current problems in fusion devices

We present a technique to efficiently solve 3D eddy current problems in fusion devices, whose structuresexhibit a geometrical symmetry. The proposed approach is based on the exploitation of symmetry viaharmonic analysis and it is suitable to treat also problems where the field sources (plasma or externalcoils) do not share the domain symmetry. A simple test case is presented to describe the methodology.Then, a more complicated geometry is considered, which represents a realistic vacuum vessel of an ITERlike fusion device (double layer structure with several portholes). The results are discussed for bothaxisymmetric and non-axisymmetric excitations in frequency domain.