Investigation of plasma facing components and vacuum vessel in RFX

The first wall components of RFX have been investigated after three years of operation and four boronization processes. The main damage is due to arcs and localized erosion. 112 new reshaped tiles have been installed and the removed ones have been carefully analysed in order to evaluate the effects due to plasma interaction. A strong redeposition of carbon and boron has been observed near the most damaged tiles. The redeposition pattern exhibits toroidal and poloidal asymmetry in agreement with the plasma flow measured in the outer region. For the first time evidence of halo currents flowing from the plasma to the vacuum vessel has been observed and their value has been estimated.