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 ?H on tungsten at high temperature is
presented using two series of atomic lines (H? and He or H? and H2) 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.