Transient release of deuterium from beryllium after plasma ion implantation
Transient release immediately following implantation was observed when large 5.1 cm diameter Be discs were implanted with deuterium ions at a flux of 7.4 x 1.0 E16 D/cm2sec. A series of experiments was performed at temperatures ranging from 333 to 800 K. The release characteristics vary, depending on whether the beryllium surface is clean or covered with a thick oxide layer. When the surface is clean, the integrated release (D/cm2) increases monotonically with temperature and then levels off at 700 K. This behaviour cannot be described with a diffusion-limited release, but is consistent with a recombination-limited release model. Furthermore, the release rate exhibits approximately a t(-1) time dependence, in good agreement with the results calculated using the model. The recombination coefficient has to be sufficiently small so that the ratio of the diffusivity to the recombination coefficient D/K(r) is greater than 1 x 1.0 E14/cm2 at 600 K and must rise sharply with temperature. When the surface of the beryllium samples is covered with a thick oxide layer, the release rate changes significantly and follows an inverse dependence on t(0.3).
Bibliographic Reference: Article: Journal of Nuclear Materials, Vol. 176 & 177 (1990) pp. 218-225
Record Number: 199110644 / Last updated on: 1994-12-02
Original language: en
Available languages: en