An analytical model for stress analysis of split toroidal field coils for a fusion device

The Toroidal Field (TF) coils of Reversed-Field-Pinch (RFP) fusion machine are subjected to much lower electromagnetic loads than those of a tokamak with equal plasma current. This allows a large number of different design options to be adopted for RFP TF coils, for an easier assembly. Therefore working conditions of these coils can different from the well studied conditions of tokamak coils. In the case of the RFX machine each TF coil is made of two semicircular half coils, connected by flexible electrical joints. The effects of electromagnetic and thermal loads have been carefully evaluated to design these coils. In particular an analytical model has been developed to study the effect of the coil in-plane forces. The half coil is modelled as a curved beam on an elastic foundation, subjected to a nonuniform load. The thermal effect is taken into account by means of an additional strain. The basic assumptions of the model, as well as the final results are presented for both the TF coil and its clamp