Hydrogen atom recombination on tungsten at high temperature: Experiment and Molecular Dynamics Simulation

Atom recombination at wall is a phenomenon involved in many plasma experiments and also in present tokamaks and future fusion plasma reactors like ITER. This exothermic surface reaction is catalyzed by the material and depends on its composition and temperature. In the MESOX experimental set-up, several methods were developed for the measurement of the recombination parameters. In this paper, a method developed for the experimental evaluation of the recombination coefficient of atomic hydrogen gamma(H) on tungsten at high temperature is presented using two series of atomic lines (H alpha and He or H beta and H-2) and the results obtained for surface temperature up to 1350 K are given. A Molecular Dynamics Simulation has been done for the recombination of hydrogen atoms on tungsten in conditions close to the experimental ones using a semi-classical collisional method. Modeling results are compared to the experimental data for two surface temperature values and a fairly good agreement was obtained. (C) 2014 Elsevier B.V. All rights reserved.