Thermodynamic and Kinetic Parameters of the Processes of Deuterium Interaction with Tungsten Protective Coatings

Abstract

The effect of radiation damage on the retention of deuterium in tungsten (W) was examined. A vacuum-arc plasma source with magnetic stabilization of the cathode spot was used for tungsten coatings preparation. W samples were treated with D ions at temperatures 300‑600 K with a fluence of (1 – 10) ·1020 D2+/m2 and ion energies of 12 keV/D2+. The influence of radiation damage on microstructure and accumulation of deuterium implanted in W samples at room temperature and after annealing have been studied. Thermal desorption (TD) spectroscopy was used to determine the D retained throughout the bulk of the sample. The structure of TD spectra represents the multi-stage process of deuterium release suggesting the trapping of gas atoms by a number of defect types. Computational evaluation of deuterium desorption within the framework of the diffusion-trapping model allows to associate characteristics of experimental TD spectra with specific trapping sites in the material. Experimental TD spectrum was fitted by assigning four binding energies of 0.55 eV, 0.74 eV, 1.09 eV and 1.60 eV for the peaks with maxima at 475, 590, 810 and 1140 K, respectively. The low temperature peak in the TD spectra is associated with desorption of deuterium bounded to the low energy natural traps, whereas the other peaks are related to the desorption of deuterium bounded to the high energy ion induced traps: monovacancies and vacancy clusters.

Keywords

• tungsten
• irradiation
• damage
• microstructure
• thermal desorption
• deuterium trapping
• activation energies
• de-trapping processes