Recrystallized graphite behavior as the first wall material in Globus-M spherical tokamak

Abstract First wall protection tiles manufactured from recrystallized graphite doped by Ti (RGTi) were extracted from the first wall of the Globus-M spherical tokamak after being used as plasma-facing components (PFCs) during more than 8000 pulses (more than 800 s). The analysis of chemical composition and structure of the irradiated tiles was performed by different methods. It was found that most of the tiles were covered with mixed layers. In the deposits the amount of absorbed deuterium was measured and minimum D concentration was found in the region of maximum power loads. Only a small amount of deuterium has been detected in the bulk of RGTi tiles exposed to plasma.