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The first design of the NbTi poloidal field (PF) coils for the EU DEMO fusion reactor has been proposed by the Swiss Plasma Center and by the Italian National Agency for New Technologies, Energy and Sustainable Economic Development. 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 (nτ ) whose value is currently unknown. Therefore, we apply our model to parametrically assess the sensitivity of the PF performance to a range of nτ 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 acceptableminimum of 1.5 K. [ABSTRACT FROM AUTHOR]

In superconducting coils for fusion applications, the cable-in-conduit (CIC) conductor is the most adopted solution. ENEA reported last year about a newly developed compact joint, successfully tested for Nb3Sn conductors in a configuration suitable for the EFDA Dipole which is currently in construction phase. The main advantages of this new concept are: low room occupancy, low price and easiness of manufacturing process. In the present paper, new results coming from the characterization of NbTi joint samples are presented, suggesting new applications for this innovative junction. A joint layout optimization study by means of an electrical simulation code is included as well. [ABSTRACT FROM AUTHOR]

The superconducting magnet system plays an important role in the framework of the design of the EU DEMO tokamak. In recent years, ENEA developed a prototype of cable-in-conduit conductor (CICC) with two low-impedance central channels to be used in the DEMO Toroidal Field (TF) coils with a graded winding pack (WP). In this paper, a model of a TF coil based on the thermal-hydraulic code 4C has been developed, including the WP, the steel casing with dedicated cooling channels (CCCs) and the two independent cryogenic circuits cooling the WP and the casing, respectively. The first part of the work analyzes the performance of the WP during a series of standard plasma pulses in normal operating conditions. In the second part different off-normal operating conditions during the plasma pulses are studied, namely the collapse of one or both central channel(s) in the most critical CICCs and the plugging of some CCCs at the most critical locations in the magnet. [ABSTRACT FROM AUTHOR]