ITER toroidal field model coil test: analysis of heat transfer from plates to conductors

Abstract

As the main objective of the toroidal field model coil (TFMC) is to demonstrate the industrial feasibility of the ITER TF coils, the TFMC design includes the particular features of these coils, such as the insertion of the conductors inside stainless steel radial plates (see Fig. 1). During ITER transients such as the safety discharge of the magnetic system, eddy currents are induced in the plates, generating a power, which is transferred into the conductor helium channels by a long diffusion process through the conductor steel and insulation, and eventually quenches the system. In this case, the delay introduced by this diffusion is a key parameter in the quench evolution. The model of this diffusion is presented. The diffusion equation is added to the thermohydraulics code gandalf, which enables to take into account the helium circulation along the channel. The ITER TFMC experiment offers an unique possibility to check this model. Specific safety discharges were intentionally initiated from 25 kA to study this phenomenon. The results of these experiments are compared with the predictions. The model proves to be quite effective and can be used for ITER. The heat conductivity and the specific heat used in the model are discussed.