Deuterium thermal desorption from vacancy clusters in tungsten

Deuterium interaction with vacancy clusters in tungsten was studied by means of thermal desorption spectroscopy (TDS). A recrystallized W foil was used as a sample, and the vacancy clusters were formed in the bulk by irradiation with 10 keV/D ions to the fluence of 3 × 1019 D/m2 and subsequent annealing at the temperature of 800 K. Then the sample was loaded with deuterium (0.67 keV/D ions with a fluence of 1 × 1019 D/m2), and TDS measurements with varying heating rates β in the range of 0.25–4 K/s were performed. The high temperature peak with the maximum at around 700 K was attributed to deuterium desorption from vacancy clusters and the detrapping energy for this type of defects was determined from the slope of the Arrhenius-like plot ln(β/Tm2) versus 1/Tm1/Tm, where Tm is the peak position. The detrapping energy calculated this way is 2.10 ± 0.02 eV.