FEM calculation of eddy current losses and forces in thin conducting sheets of test facilities for fusion reactor components

An efficient finite element formulation of the eddy current field in thin conducting sheets has been developed coupled to a description of the magnetic field by a gauged magnetic vector potential. The numerical problems associated with the thin conductors have thereby been eliminated. Results of computations on a model of the TOSKA Upgrade test facility are presented. The aluminium radiation shields are not in danger; the stresses acting upon them are negligible. This is due to their being located relatively far from the superconducting coil. Only parts of the supply lines near the connecting flange of the vacuum vessel experience considerable stress. Their reinforcement under rapid changes may be necessary. The vacuum vessel is not endangered, since its wall of 20 mm thickness easily withstands the stresses due to the induced eddy currents. Normal pressures of up to about 50 t/m² occur at the LN2 shield. This makes modifications of its structure necessary