FIRST WALL UPGRADE FOR THE REVERSED-FIELD PINCH RFX

The inner surface of the RFX vacuum vessel is protected by a first wal l made up by 2016 polycrystalline graphite tiles. Due to the dimension s of the largest ports, inspection, maintenance and replacement of the first wall components can be carried out only by a remote handling sy stem. Inspections performed during the first four years of operation s howed evidence of some plasma surface interaction not only on the grap hite tiles, but also on small portions of the vacuum vessel in the int erspace between two tiles. Erosion phenomena were observed in the area which corresponds to the insulated poloidal gaps of the stabilizing s hell that surrounds the vacuum vessel. New graphite tiles to be instal led in these regions were designed, with a shape which completely clos es the interspace in the poloidal direction between the tiles. During the last shut down, in 1995, all the 112 tiles were successfully repla ced by means of the remote handling system.