The ITER In-Vessel Coils – design finalization and challenges

Abstract ITER In-Vessel Coils (IVCs), resistive magnets to be installed in close proximity to ITER plasma to compensate fast perturbations of the plasma itself, have undergone a comprehensive revision of their requirements and operational loads, leading to design modifications and R&D activities. An update of the plasma operating scenarios has been done and the maximum currents during transient plasma events have been assessed considering actual operating currents and the surrounding vacuum vessel support structure leading to more representative load cases. The main IVC component modifications are the conductor material and the winding pack support structure. Phase 1 of the conductor procurement involving two suppliers has been completed and the supplier selection for the main production is ongoing. Additional modifications include the joints, where Cu brazing has been replaced by welding, and the conductors are not brazed to the winding pack bracket but clamped. Bracket mockups for the coils have been completed identifying welding parameters and corresponding non-destructive examination (NDE), while different designs of electrical insulating breaks (IB) using Alumina have been tested against pressures up to 80 bars on top of the electrical characterization. A summary of the key challenges experienced towards design finalization is presented.