Speaker
Description
Nearly two decades after achieving its first plasma in 2006, the Experimental Advanced Superconducting Tokamak (EAST) continues to serve as a key device for superconducting magnet technology, being the first tokamak to employ both toroidal and poloidal superconducting coil systems. Its Toroidal Field (TF) coil system consists of sixteen coils, each approximately 4 m in height, operated at cryogenic temperatures around 4.5 K through forced-flow cooling with supercritical helium (SHe) at about 3.8 bar. Reaching these operating conditions requires a prolonged thermal transient—the magnet cooldown—during which the coil temperature is progressively reduced from ambient to cryogenic temperature.
The Cryogenic Circuit, Conductor and Coil (4C) code, developed at Politecnico di Torino more than 15 years ago, is a dedicated thermal-hydraulic simulation tool for superconducting fusion magnets. It has undergone extensive verification and validation exercises across a wide range of relevant transients, from fast quench scenarios to slow cooldown processes, and is increasingly used to support the design and safety assessment of magnet systems for next-generation tokamaks.
The 4C code is here applied to model the cooldown of the EAST TF coils, representing the first validation of the tool against experimental data for a full-magnet cooldown in an operational tokamak. The simulation employs measured boundary conditions—namely the inlet temperature and the inlet/outlet pressures of the SHe flow—and predicts the evolution of the outlet temperature. These results are then quantitatively compared with experimental measurements to assess the predictive accuracy of the thermal-hydraulic model.
This validation effort represents a significant step towards the qualification of the 4C code for its use in future fusion devices, particularly in contexts where licensing processes increasingly require certified, validated thermal-hydraulic tools. Its successful benchmarking against EAST data will further strengthen its position as a reference tool for superconducting magnet thermal-hydraulic modeling. It will indeed be reliably applied also to the design and operation of the magnet system of the China Fusion Engineering Test Reactor (CFETR).
Acknowledgements
This work was supported by the Comprehensive Research Facility for Fusion Technology Program of China under Contract (No. 2018-000052-73-01- 001228).
