Final Design of ITER In-Vessel Coils and Manufacturing of In-Vessel Coil Conductor

Following a decision made at the ITER Council in November 2013, two types of in-vessel coils (IVCs), namely, edge-localized mode (ELM) coils to mitigate ELMs and vertical stability (VS) coils to provide vertical stabilization of the plasma, have been incorporated in the ITER baseline design. The in-vessel environment is severe, characterized by large transient electromagnetic fields, high radiation flux, and high temperature. To withstand this environment and provide the required functionality, a “mineral insulated conductor” (MIC) technology has been selected for the IVC conductor. It consists of an axially water-cooled copper conductor surrounded by magnesium oxide insulation and a stainless steel jacket. A major advantage of the coil design is the choice of the same conductor material and dimensions for both VS and ELM coils, long conductor length which eliminates the need for any internal joints, and Cu welding for the joints between coils and feeders. In situ winding of the VS coils is asking for the development of a creative solution for the unspooling, straightening, precise winding tools, bending, forming, and metrology processes in a tight and congested environment. Mock-ups for design verification and manufacturing feasibility have been produced, in particular, for the bracket manufacture and to perform thermal and mechanical fatigue testing on an ELM control coil winding pack assembly. Installation trials of a half-size ELM control coil have been performed to verify the feasibility of the assembly procedure. This article will give an overview of the IVC design status and the progress of ITER IVC conductor manufacturing.