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Description
The Toroidal Field system of the JT-60SA tokamak comprises 18 NbTi superconducting coils. In each TF coil (TFC), 6 Cable-In-Conduit Conductor (CICC) lengths are wound in 6 double-pancakes (DP) and carry a nominal current of 25.7 kA at a temperature of 4.7 K. After fabrication and before delivering to Japan, each coil is tested in the Cold Test Facility (CTF, CEA Saclay), the test program including a quench for each coil. In order to ensure the tested magnet safety, a regular quench detection system is based on compensated voltages. A coupled model has been developed including: - One model of the external cryogenic circuit with SimCryogenics code (new tool developed by CEA-SBT with process-control possibilities) comprising the pump, an heat exchanger, control valves, quench relief valves and a quench tank; - 12 THEA (Thermal, Hydraulic and Electric Analysis) models for the 12 conductors pancakes of the coil. The quench performed on coil C11 (experimental quench starting on a lateral pancake) and C13 (experimental quench starting on a central pancake) has been simulated, representing the increase of inlet helium temperature up to 7.46 K leading to the quench, followed by the safety current discharge. The simulation results (THEA/SimCryogenics coupled model) are compared with the test measurement signals, in particular the helium temperatures, pressures and mass flows at the extremities of the conductors and coil. Results regarding the external cryogenic loop are detailed and the calculated conductor temperature is also presented. In addition, results of THEA/SimCryogenics simulations applied to coil C11 quench test are compared to previous results from SuperMagnet (THEA/Flower) simulations. This work can also help validating SimCryogenics and Flower codes on a real cryogenics magnet configuration in view to recommend their use in similar models for ITER magnets quench studies and safe operation.
| Submitters Country | France |
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