Material Migration Patterns and Overview of First Surface Analysis of the JET ITER-Like Wall
Following the first JET ILW operations a detailed in situ photographic survey of the main chamber and divertor was completed. In addition, a selection of tiles and passive diagnostics have been removed from the vessel and made available for post mortem analysis. From the photographic survey and results from initial analysis, the first conclusions regarding erosion, deposition, fuel retention and material transport during divertor and limiter phases are drawn. The amount of deposition on inner and outer base divertor tiles and remote divertor corners has reduced by more than an order of magnitude. Deuterium retention ratio in mainly beryllium deposits has reduced by a factor of five and carbon concentrations are low. There is however beryllium deposition at the top of the inner divertor. The net beryllium erosion rate from the midplane inner limiters is found to be higher than for the previous carbon wall campaign although further analysis is required to determine the overall material balance due to erosion and re-deposition.