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

Abstract

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.