Modeling of Surface Deformations during Plasma Disruptions

Abstract

Plasma-facing components (PFCs) in tokamak-type fusion reactors are subjected to intense heat loads during plasma disruptions, causing melting and evaporation of the metallic surface layer. Simultaneously, large eddy currents are induced in the PFCs, which interact with the large background magnetic field, hence producing substantial forces that have a strong influence on component integrity and lifetime and may cause surface deformations of the melt layer. The shapes of the free surface of the molten layers of pure tungsten metal that are produced under the influence of external body forces arising from electromagnetic fields were studied by using a two-dimensional transient computer program that solves the equations of motion in a two-phase system, with monotonically varying external body forces both in space and in time. It is demonstrated that external body forces, having an outward direction from the plane of the test piece, influence the free surface significantly. Results are presented for different disruption times and for a range of external body forces varying linearly in space and in time. However, it should be stated that the description of the problem and the conclusions are qualitative and represent only a first step in the study of this very complex problem.