Hydrogen isotope exchange in beryllium co-deposits: modelling and experiment

In order to understand the interaction mechanisms between hydrogenic species and beryllium co-deposits, a 1D Diffusion Trapping Model of Isotopic eXchange in Be (DITMIX) is developed. Hydrogen depth profiles from DITMIX are in good agreement with those measured by 15N-NRA on pre-characterised 600 nm thick Be:H layers (H/Be = 0.04), which were irradiated by D ions with a low flux of 1017 m−2 s−1 and an energy of 5 keV D−1, for different fluences and surface temperatures. Hence DITMIX provides a qualitative understanding of the isotope exchange mechanisms, although modelled versus measured D profiles show less agreement in the bulk, casting some doubt on the processes involved. For such low fluxes, DITMIX shows that the main factors determining isotopic exchange are the irradiation fluence and the surface temperature.