Eddy currents benchmark analysis in ITER

The authors present the results of a benchmark analysis among different computational methods used to solve the problem of the eddy current circulation in the conductive structures of a tokamak. The scope of the work, which was carried out in the framework of the ITER (International Thermonuclear Experimental Reactor) conceptual design activities, was to gain knowledge on the approximations due to the geometric descriptions and solution methods in the evaluation of the electromagnetic effects. The benchmark analysis was performed using one simplified axisymmetric model, one 3-D shell finite elements code, and one fully 3-D finite elements code (EC). The results reported include global parameters, such as the total circulating current, ohmic power dissipated, and the forces on the structure or on parts of it, and local values of the current density. The results of the analysis show that there is a significant difference in the results of 3-D shell and fully 3-D codes. The obvious reason is the additional degrees of freedom described in the fully 3-D codes, thus taking into account additional possibilities for the eddy current flow