Thermohydraulical Analysis and Fast Assessment of Operating Windows for JT-60SA TFC Commissioning

JT-60SA Toroidal Field Coils (TFC) comprise each a Winding Pack (WP), with 6 Cable-In-Conduit Conductor (CICC) lengths wound in 6 double-pancakes operating at 25.7 kA nominal current and 4.7 K temperature as well as stainless steel casing cooled by forced flow channels. Second phase of Integrated Commissioning (IC) have been performed during 2023 with current discharge and induced AC losses in the CICC and eddy currents in the structures. A Fast Assessment of Operating Window (FAOW) model was developed for this purpose and permits to assess heat loads inputs, the heat transfer from casing to WP with inertia effect and time delay, and the cooling capacities (through heat exchanger). This FAOW model is coupled to Superconductors Thermohydraulical and Resistive Electrical Analytical Model (STREAM) and permits to evaluate helium pressure and temperature increase in cooling loop. The IC 18 kA current discharge measurements are compared to calculated results thus validating models and analyses. Predictive calculated results for other current discharge values (15, 18, 20, 23.7 and 25.7 kA) are presented and discussed with the maximal helium pressure limits, and safety aspects (induced relief valves opening or not). These analyses of current values operating windows have been confirmed by further plasma operation at 23.7 kA. Even if the limits of the model are discussed, the main interest consists of rapid execution time duration (only few minutes) compared to numerical codes (several hours). This work and fast analysis tool and model (FAOW-STREAM) can be also useful for further performances analyses in view to recommend their use in similar ITER or EU-DEMO magnets, with possibility of real-time feed-forward calculations/control.