Published: Jan 1987
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Helium is readily trapped by vacancies, and this trapping reduces its mobility considerably. Trapping also influences the sink strengths of the sinks in the material, and in this paper we describe calculations for these sink strengths using a recently developed numerical method for calculating the concentration profiles around a sink embedded in a lossy continuum. We find that under some conditions the sink strengths can differ appreciably from the values for a noninteracting mobile defect. Using these sink strengths, we then discuss the effect of trapping on the effective diffusion coefficient of the helium. We find that the effective diffusion coefficient of the helium is very close to the value obtained when these changes to the sink strengths are neglected. This is because, in general, the sink strength for free helium atoms is increased whereas that for the trapped helium is decreased.
rate theory, point defects, helium trapping
Scientist, AERE Harwell, DIDCOT, Oxon OX11 ORA,