The numerical analyses carried out to assess the effectiveness of an e
lectromagnetic shield are presented in the paper. The shield should re
duce the field errors on the magnetic configuration due to the gaps of
a conducting shell of a nuclear fusion device, already in operation.
The shield dimensions are limited by other components, so the actual e
ffectiveness had to be accurately computed. The finite element method
was used for 3-D eddy current analysis and the results were compared w
ith measurements on the actual shell. The stray magnetic field in the
plasma region with the shielded gap resulted 30% lower than with the u
nshielded gap.