The interaction of the ITER first wall with magnetic perturbations

TL;DR

This paper investigates how magnetic perturbations interact with ITER's first wall, especially the effects of tiled surfaces on magnetic forces and perturbation behavior, which is crucial for disruption mitigation.

Contribution

It introduces a practical method to incorporate the subtle electromagnetic effects of tiled surfaces into plasma simulations for ITER.

Findings

Tiled surfaces can influence magnetic perturbations significantly.

Short timescale and localized perturbations are more affected by the tiles.

Electrical separation of tiles introduces indeterminacy in magnetic interactions.

Abstract

Mitigation of the multiple risks associated with disruptions and runaway electrons in tokamaks involves competing demands. Success requires that each risk be understood sufficiently that appropriate compromises can be made. Here the focus is on the interaction of short timescale magnetic-perturbations with the structure in ITER that is closest to the plasma, blanket modules covered by separated beryllium tiles. The effect of this tiled surface on the perturbations and on the forces on structures are subtle. Indeterminacy can be introduced by tile-to-tile shorting. A determinate subtlety is introduced because electrically separated tiles can act as a conducting surface for magnetic perturbations that have a normal component to the surface. A practical method for including this determinate subtlety into plasma simulations is developed. The shorter the timescales and the greater the localization, particularly in the toroidal direction, the more important the magnetic effects of the tiles become.