The Influence of External Body Forces on the Molten Depths in Tungsten during Plasma Disruptions

Abstract

Plasma-facing components 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 plasma-facing components, which interact with the large background magnetic field, hence producing substantial electromagnetic loads that have a strong influence on component integrity and lifetime. The depths and shapes of the molten layers of pure tungsten metal, which are produced when a high heat load strikes the surface of the material during a plasma disruption under the simultaneous influence of external body forces arising from electromagnetic fields, were studied by using a two-dimensional transient computer program that solves the equations of continuity, momentum, and energy, with monotonically varying external body forces. It is demonstrated that external body forces, having an outward direction from the plane of the test piece and with different gradients with respect to the radial direction, influence the shapes and depths of molten layers to a significant extent. Results are presented for a range of energy densities, disruption times, and gradients of linearly varying external body forces.