The tritium imaging plate technique was used to visualize the penetration profiles of hydrogen (tritium) loaded into pure tungsten via dc glow discharge at 473 to 673K. The penetration profile consisted of two components: a highly localized one in the near-surface region (sub-mm in depth) and a deep penetrating one (several mm in depth). An apparent hydrogen diffusion coefficient was determined from the latter, given by:

D = 3 x 10-7exp[-0.39(eV)/kT]

The localized near-surface one was attributed to hydrogen trapping, with a trapping energy of 0.84eV.

T.Otsuka, T.Hoshihira, T.Tanabe: Physica Scripta, 2009, T138, 014052