The ITER magnet systems are composed of twenty toroidal field (TF) coils, a Central Solenoid (CS), nine poloidal field (PF) coils, and sixteen Correction Coils (CC). This paper will summarize the features of the design with emphasis on changes and recent progress in the magnet R&D program.

The number of PF coils has increased from seven to provide more flexibility in operation. All of the PF coils are self supporting for radial loads by using heavy walled, stainless steel conduits with cabled NbTi and copper strands. Eight of the coils operate at 4.5K and one coil operates at a temperature of 3.8 K to achieve the required mega-ampere turns under the expected field conditions. A double turn insulation with a metallic screen is used in each coil to provide for impending fault detection.

The CC also use NbTi conductor in cable in conduit form. Four coils are located on top of the TF coil cases, eight coils outside the PF coils around the sides of the machine, and four coils below the PF coils under the machine. The CC are being designed to compensate for expected tolerance errors in coil construction and installation.

The TF coils and CS have evolved in detail, but not significantly in concept, since the Interim Design was solidified. The TF conductors are individually supported within radial plates that form the winding pack for a TF coil which is, in turn, supported by a case. The CS is layer wound with a heavy walled conductor that is a primary structural element. Essential features for fabrication of the TF and CS coils are being duplicated in model coils now under construction. Conductor performance will be demonstrated with insert coils for CS and TF conductors to be operated within the 13 T, 640 MJ, CS model coil. Essentially all of the Nb3Sn strand and cabling is complete for the model coils, as well as jacketing for the CS model coil. Major tooling items are complete and the status of fabrication and schedule for testing will be summarized.