Primary Quench Detection Analysis for DTT Central Solenoid and Poloidal Field Coils

The Central Solenoid (CS) and the Poloidal Field (PF) coils of the DTT tokamak (Divertor Tokamak Test facility, currently being built in the site of ENEA C.R. Frascati – Italy) are operated in dynamic mode and, even in normal operation, the self and mutual voltages induced across each coil are of the order of magnitude of ≈100 V. In DTT, these coils will be realized with superconducting materials and, as a consequence, a reliable and fast quench detection system is required in order to protect the magnets. Being the quench signals 4 orders of magnitude smaller than the operating voltages, the cowound (CW) technology must be adopted for the quench sensors, the only degree of freedom being among a wiring configuration merely aligned with the coil winding (CWA) or aligned and twisted to the coil winding (CWA&TW). In this study, a model of the DTT poloidal magnetic system has been developed up to the details of the single windings (layer or pancake) of the various coils. CWA sensors have also been implemented in the model. Signals coming from the magnetic system and the CWA sensors during the Single Null plasma event have been simulated and compared. The analysis has been carried out up to the level of the elementary winding of each coil, using a lumped parameters circuital model. Finally, a simple theory has been developed aimed at the estimations of the improvements coming from the CWA&TW architecture.