Behaviour of a tungsten coated molybdenum poloidal limiter in FTU tokamak

Abstract A tungsten coated molybdenum poloidal limiter has been tested in the FTU tokamak. The evidence of no deterioration of macroscopic plasma parameters in standard sawtooth discharges, with respect to other medium and high Z materials, has been confirmed by post-mortem analysis of the limiter. Negligible traces of erosion by sputtering or thermal loads were found in the limiter regions not interested by abnormal events. A large part of the macroscopic damages around the outer and inner equatorial plane is believed to be caused by runaway electron fluxes during disrupting discharges.