PLASMA SURFACE INTERACTION IN ITER TOKAMAK DISRUPTION SIMULATION EXPERIMENTS/

In evaluating the lifetime of plasma-facing components for the Interna tional Thermonuclear Experimental Reactor (ITER) against nonnormal hig h heat loads, credit is taken from the existence of a plasma shield th at protects the target from excessive evaporation. Formation and physi cal properties of plasma shields are studied at the dual plasma gun fa cility, 2MK-200, under conditions simulating ITER hard disruptions and edge-localized modes (ELMs). The experimental results are used for va lidation of the theoretical modeling of the plasma/surface interaction . The important features of the non-local thermodynamic equilibrium pl asma shield, such as temperature and density distribution, its evoluti on, the conversion efficiency of the energy of the plasma stream into total and soft X-ray radiation from highly ionized evaporated target m aterial, and the energy balance in the plasma shield, are reproduced q uite well. Thus, realistic modeling of ITER disruptive plasma/wall int eraction is now possible. Because of the rather small target erosion i n the simulation experiments, material erosion for ITER typical disrup tions and ELMs cannot be evaluated from these simulation experiments, This requires additional simulation experiments with hot plasma stream s of longer pulse duration and a separate numerical analysis, which ca n now be performed with validated theoretical models.