Deuterium retention in sintered boron carbide exposed to a deuterium plasma

Depth profiles of deuterium up to a depth of 10 μm have been measured using the D(3He,p)4He nuclear reaction in a resonance-like technique after exposure of sintered boron carbide, B4C, at elevated temperatures to a low energy (≈200 eV/D) and high ion flux (≈1021 m−2 s−1) D plasma. The proton yield was measured as a function of incident 3He energy and the D depth profile was obtained by deconvolution of the measured proton yields using the program SIMNRA. D atoms diffuse into the bulk at temperatures above 553 K, and accumulate up to a maximum concentration of about 0.2 at.%. At high fluences (⩾1024 D/m2), the accumulation in the bulk plays a major role in the D retention. With increasing exposure temperature, the amount of D retained in B4C increases and exceeds a value of 2 × 1021 D/m2 at 923 K. The deuterium diffusivity in the sintered boron carbide is estimated to be D = 2.6 × 10−6exp{−(107 ± 10) kJ mol−1/RT} m2 s−1.