The Effect of Annealing on the Transient Deuterium Permeation Characteristics of Tungsten

Effect of annealing on the transient permeation behavior of deuterium implanted into pure tungsten was investigated. Permeation experiment was carried out with pure tungsten foils (34 mm in diameter, 25 micro-m in thickness, and 99.5% purity) annealed at 1273 K for 3 hours in vacuum and unannealed one. Those permeation characteristics at transient state were analyzed by TMAP4 code. As a result, the feature of the trap site in the unannealed tungsten specimen was revealed that which has about 0.9 eV trap energy and 40ppm-trap density. By the analysis of the permeation behavior through the annealed tungsten, above trap sites disappeared by specimen annealing, and the permeation through annealed tungsten was found to be expressed by simple diffusion equation with the effective diffusion coefficient. However, it may involve the trapping parameter, which is virtually indistinguishable from reduction of diffusion coefficient, in itself.