Laboratory studies of H retention and LiH formation in liquid lithium

• Absorption and thermal desorption experiments of hydrogen isotopes in liquid lithium have been performed at exposure temperatures up to 400 °C.
• The kinetics of the involved processes indicate a two-stage mechanism for hydride production.
• TDS peaks at temperatures well below the expected one for thermal decomposition of the hydride were systematically recorded, although only a small fraction of the absorbed gas was released during the TDS cycle.
• The absorption of H2 in a D2-loaded sample was investigated at two temperatures, and no obvious influence of the preexisting species in the rate of absorption of H2 was seen.
• Deuterium absorption takes place at a higher rate than that of hydrogen.

Laboratory experiments on H/D retention on liquid lithium followed by thermal desorption spectrometry (TDS) have been performed at Ciemat. Two different experimental set ups were used in order to expose liquid Li to hydrogen gas or to hydrogen glow discharge plasmas at temperatures up to 673 K. In the present work the results concerning the gas phase absorption are addressed. Two different kinetics of absorption were identified from the time evolution of the uptake. Alternate exposures to H2 and D2 were carried out in order to study the isotope exchange and its possible use for tritium retention control in Fusion Reactor. Although important differences were found in the absorption kinetics of both species, the total retention seems to be governed by the total sum of hydrogenic isotopes, and only small differences were found in the corresponding TDS spectra, on which evidence of some isotope exchange is observed. The results are discussed in relation to the potential use of liquid lithium walls in a Fusion Reactor.