Permeation and trapping of hydrogen in Eurofer97

Abstract

Diffusion and trapping of hydrogen isotopes in fusion materials need to be fully described in order to evaluate permeation and retention in fusion reactors walls and breeding blankets. Hydrogen gas permeation experiments have been conducted on Eurofer97 with pressures ranging from 101to 105Pa and temperatures between 473 K and 673 K, resulting in solubility K(T) (mol m−3 Pa−12)= 1.76⋅10−1exp(−0.27(eV)kBT), diffusivity D(T) (m2 s−1) =2.52⋅10−7exp(−0.16(eV)kBT)and permeability Φ(T) (mol m−1 Pa−12s−1) =4.43⋅10−8exp(−0.43(eV)kBT). Trapping parameters have been investigated using thermal desorption spectrometry of deuterium-loaded samples coupled with parametric optimization, leading to detrapping energies Edt,1=0.51eV, Edt,2=1.27eV, Edt,3=1.65eVand densities Nt,1=6.01⋅1025 m−3, Nt,2=6.44⋅1022 m−3, Nt,3=3.88⋅1023 m−3. This parametric optimization is performed using a kinetic surface model: the contribution of this model is compared to the results given by solubility and recombination rate models.

Keywords

• Permeation
• Trapping
• Eurofer97
• Hydrogen
• Thermal desorption spectrometry
• MHIMS