Primary and secondary metallic PFC damage induced by runaway electron dissipation in FTU

Runaway electron (RE) interaction with plasma-facing components (PFCs) has been documented to lead to deep volumetric melting and thermal shock driven material explosions followed by extensive wall cratering. This work reports a post-mortem FTU investigation that covers the primary localized RE-induced damage directly caused by beams striking poloidal or toroidal molybdenum (Mo)-based limiters and the subsequent secondary non-localized RE-induced damage inflicted on nearby limiter tiles by the mechanical impact of fast up to km/s solid debris violently ejected during the direct RE-PFC interaction. Early indications on the resilience of tin liquid limiters to RE incidence are also presented.