Modeling of W7-X superconducting coil cool-down using the 4C code

The recently developed 4C thermal-hydraulic code is validated here against experimental data from the cool-down of a non-planar coil of the Wendelstein 7-X stellarator from room temperature to the superconducting transition temperature of ∼10 K, performed during the cold test of the full set of coils at the cryomagnetic test facility of CEA Saclay. The computed results, i.e., temperature and mass flow rate evolutions in different coil components (helium, casing, etc.) are shown to be in good agreement with the experimental data. The simulations also show that during the transient the hot spot temperature inside the coil can be up to ∼3–4K higher than what is seen on the casing surface