Modelling of lithium erosion and transport in FTU lithium experiments

Abstract The ERO code has been used to simulate lithium erosion, transport and re-deposition from liquid lithium limiter experiments in FTU. Two different operational cases from LLL experiments with different plasma parameters and surface temperature are modelled. According to the effective lithium sputtering yields, for both cases the lithium erosion is mainly due to physical sputtering rather than evaporation. Furthermore, the modelled re-deposition fraction of evaporated lithium is much higher than that of sputtered lithium, which is due to the shorter ionisation mean free path of thermal lithium atoms. Therefore, the evaporation erosion effect can be neglected compared to physical sputtering when the surface temperature is below 450 °C. According to the simulations, most of the lithium impurities exist in the form of Li+, and the main plasma contamination by lithium ions is low because most of eroded lithium particles are not transported into the core plasma and stay outside of the LCFS.