Performance analysis of the NbTi PF coils for the EU DEMO fusion reactor

The first design of the NbTi Poloidal Field (PF) coils for the EU DEMO fusion reactor has been proposed by the Swiss Plasma Center (SPC) and by the Italian National Agency for New Tech-nologies, Energy and Sustainable Economic Development (ENEA). The thermal-hydraulic (TH) performance analysis of the PF coil system presented in this work has been carried out using the state-of-the-art 4C code. The minimum temperature margin and the TH response of the coils to the heat deposition due to AC losses are computed in two different plasma scenarios, using a single time constant (nt) whose value is currently unknown. Therefore, we apply our model to parametrically assess the sensitivity of the PF performance to a range of nt values. The calculations are also performed taking into account that the high void fraction design of the conductor leads to the opening of a channel due to the Lorentz force. For all situations considered here, the 4C code predicts that the temperature margin never goes below the acceptable minimum of 1.5 K