Plasma/Surface Interaction in ITER Tokamak Disruption Simulation Experiments

Abstract

In evaluating the lifetime of plasma-facing components for the International Thermonuclear Experimental Reactor (ITER) against nonnormal high heat loads, credit is taken from the existence of a plasma shield that protects the target from excessive evaporation. Formation and physical properties of plasma shields are studied at the dual plasma gun facility, 2MK-200, under conditions simulating ITER hard disruptions and edge-localized modes (ELMs). The experimental results are used for validation of the theoretical modeling of the plasma/surface interaction. The important features of the non-local thermodynamic equilibrium plasma shield, such as temperature and density distribution, its evolution, the conversion efficiency of the energy of the plasma stream into total and soft X-ray radiation from highly ionized evaporated target material, and the energy balance in the plasma shield, are reproduced quite well. Thus, realistic modeling of ITER disruptive plasma/wall interaction is now possible. Because of the rather small target erosion in the simulation experiments, material erosion for ITER typical disruptions and ELMs cannot be evaluated from these simulation experiments. This requires additional simulation experiments with hot plasma streams of longer pulse duration and a separate numerical analysis, which can now be performed with validated theoretical models.