Deuterium ion-driven permeation in tungsten with different microstructures

Deuterium ion-driven permeation through three different types of W specimens with varying grain size was measured as a function of temperature (500K < T < 1100 K). The steady-state permeation flux was microstructure independent and the inverse relationship with specimen thickness holds within a factor of two over the entire temperature range. In most cases, a maximum in the permeation flux was observed at T congruent to 800K and this peak structure was interpreted to result from the deviation from diffusion-controlled transport. The effective diffusivities derived from lag time measurements were two to three orders of magnitude lower than Frauenfelder's values.