Modeling of Quench in the ITER Poloidal Field Coils

The
SuperMagnet
suite of code is here applied to study the Poloidal Field (PF) and Correction Coils (CC) and their cryogenic distribution during a quench in the PF coils. In the model, more than 65 km of conductors, bus-bars, 3 km of pipes, the cold circulator, several bypass and control valves are implemented to reproduce the cryogenic circuits. The quench is simulated with an external heat disturbance at the location characterized by the lowest temperature margin during the plasma scenario. Two different approaches have been followed. In the first approach, the coils are initially assumed at their nominal conditions in “cold” state (4.4 K), before the beginning of the operating cycle. In the second approach, the initial conditions of the quench simulation correspond to those obtained in the time instant at which the lowest temperature margin is found during the plasma scenario. The main parameters to be set for the intervention of the quench protection system (threshold voltage and validation time) are finally discussed.