Experimental measurements and modeling of the deuterium release from tungsten co-deposited layers

摘要

The release of deuterium from sputter magnetron produced tungsten co-deposit layers is studied by thermal desorption mass spectrometry and modelled with the diffusion reaction codes TESSIM and FACE. Layers up to ?～?2 μm thick, produced at substrate deposition temperatures up to 513 K are modeled. TESSIM simulations are found to require activity from at least nine traps in the range1.0?2.5eV in order to reproduce the experimentally observed desorption. FACE simulations, which utilize a quasi-continuous distribution of traps, suggest some discreteness in trapping energy above ?～?1.5 eV, but smoothness in the distribution below. Both codes indicate a quasi-exponential decrease in trap concentration with trap energy. When examined for predictive capability, the developed tungsten co-deposit models accurately reproduce experimental changes in the desorption heating rate from 0.3 to 3 Ks?1,and give reasonable agreement with experimentally different layer thicknesses and deposition temperatures in the parameter ranges explored. Measured D/W ratios in the co-deposits are also found to be in good agreement with literature based predictive scalings.