JT-60SA TF Coil Testing Cooling Prevision

The JT-60SA Toroidal Field coil design has been modified resulting in considerable material savings. The casing cooling loop is important during the beginning of cooldown. This study models the cooling phase foreseen for coil testing and coil operation. Data and experience gathered during the extensive cooling tests performed on 70 large W7-X coils at the CEA (Saclay) cryomagnetic test facility provide the basis knowledge to model and forecast the thermal behavior of other large magnets for thermonuclear fusion. Using coil material thermal properties, refrigeration limitations, procedure and control, a simple model of JT-60SA TF coil winding and casing cooling is proposed. Thermal gradients inside the coil are evaluated and discussed. The calculated cooldown time and the required cryogenic power will be used as design input for the coil testing facility.