Tore Supra Superconducting Toroidal Magnetic Field System

We review the main design choices for the toroidal field system and associated cryogenic system for Tore Supra, which introduced the use of 1.8 K superfluid helium as coolant for a large NbTi magnet system. The main steps of the system commissioning are presented, with a description of the main difficulties encountered, showing the evolution of the monitoring and of the safety system to take into account the lessons drawn from the first operating experience. The impact of plasma operations such as plasma initiation, long plasma discharges, and disruption is given in detail, highlighting their impact on cryogenics, which remains in all cases weak. The fast safety discharges (FSDs) of the system can disturb normal operation. Origin of and statistics about FSDs are discussed, detailing efforts to decrease their number. Finally, maintenance and monitoring of the cryogenic system and of the various sensors are presented with some consideration regarding the aging of the system and its overall availability. Details are given regarding minor failures on components all along the operation. Overall, the accumulated experience is certainly a useful tool to prepare the manufacture and operation of the ITER superconducting magnets despite the differences in design and size. (authors)