Thermal desorption of deuterium implanted into beryllium

By means of TDS measurements it is shown that the desorption of deuterium from Be implanted with 5 keV D-ions to fluences, Φ, from 1 x 1020 D/m2 to 1 x 1021 D/m2 proceeds in one high-temperature stage B, while at Φ≥1.2 x 1021 D/m2 one more stage A appears. The desorption maximum A is narrow and consists of two peaks A1 and A2 at about 460 K and 490 K, respectively. Peak A1 is attributed to the desorption of deuterium from the walls of opened channels formed under D-ion implantation. Peak A2 is a consequence of the opening of a part of bubbles/closed channels to the outer surface. The position of maximum B, Tm(B), shifts noticeably and nonsteadily on the fluence in a range 850-1050 K. The origin of this maximum is the liberation of D-atoms bound at vacancy complexes discussed previously by Wampler. The dependence of Tm(B) on the fluence is governed by the interaction of freely migrating D-atoms with arrangements of fully closed or partly opened gas cavities which are created under temperature ramping, but differently in specimens implanted with D-ions to different fluences. (orig.)