Visualization of hydrogen depth profile by means of tritium imaging plate technique: determination of hydrogen diffusion coefficient in pure tungsten

The tritium imaging plate (TIP) technique has been applied to visualize penetration profiles of hydrogen (tritium) loaded in pure tungsten (W) by a dc glow discharge at a temperature ranging from 473 to 673 K. The penetration profile consists of two components, i.e. a highly localized one in the near-surface region (sub-mm in depth), and another, deep penetrating one (several mm in depth). An apparent hydrogen diffusion coefficient is determined from the latter to be , which agrees well with the extrapolation of Frauenfelder's data obtained at elevated temperatures. The near-surface localized one is attributed to hydrogen trapping with a trapping energy of 0.84±0.04 eV.