Detailed electromagnetic numerical evaluation of eddy currents induced by toroidal and poloidal magnetic field variation and halo currents

An efficient modeling of fine air-gaps in tokamak in-vessel components for electromagnetic analyses

“…Until recently, the effective resistivity method (ERM) [13,14] has been employed as a well-known method to compensate simplification of neglecting fine structures in EM analysis, in spite of its physical limit that, for instance, the effective resistance may not be exactly consistent with the realistic behavior depending on the time constant of the time varying magnetic flux. In the framework of ERM, anisotropic assignment of the resistivity has been regarded as a quite natural way applying the effective resistivity instead of their bulk resistance with respect to the disturbance of current flow due to the fine structures, for instance eddy current breaks or air gaps.…”

“…It is found as a typical procedure to solve first the FE model with equivalent electrical excitation for the target components including their detail structures. Loading linear time varying external current along a certain axis, the overall voltage drop can be evaluated with a constraint for the time derivative of MVP, which is imposed as a constant voltage, so that one can estimate the effective resistivity along the specific axis of a simplified model without fine structure [13,14]. In spite of advantage of its simplicity, the current flow pattern of the effective resistivity calculation will not be consistent with the actual distribution of eddy current in the fine structure so that an exact estimation of the effective resistivity is not so trivial to be approximated to the anisotropic DC resistance.…”

He-cooled demo divertor: Design verification testing against mechanical impact loads

“…Following [3], different electromagnetic transients, such as plasma disruptions and vertical displacement events (VDEs), could occur during off-normal Tokamak operations resulting in the induction of eddy currents (in the conducting components) and related EM loads [4][5][6]. A detailed evaluation of the impact of these plasma current transients on divertor fingers needs a complex EM model in which toroidal and poloidal magnetic field variations, as well as Halo currents, have to be considered.…”

Engineering aspects of integration of ITER divertor diagnostics

“…The interaction between the currents induced by TFV and HC and the toroidal magnetic field generates in-plane forces; in particular, it induces a traction force during the TQ (pulling the component toward the plasma) and a pressure force during the HC and the CQ phase (pushing the component against the vessel). Out-of-plane forces could be even generated by the misalignment between these poloidal currents and the poloidal magnetic field; in any case, it has been shown that these forces have a minor effect with respect to the out-of-plane forces caused by Poloidal Field Variation (via interaction with the toroidal magnetic field) [3].…”