DEVELOPMENT OF B4C-CARBON FIBER-COMPOSITE CERAMICS AS PLASMA-FACING MATERIALS IN NUCLEAR-FUSION REACTOR (PART 3) - HEAT-RESISTANCE EVALUATION BY ELECTRON-BEAM IRRADIATION AND BY IN-SITU PLASMA DISCHARGE IN JT-60

The plasma facing component (PFC) in nuclear fusion reactors such as d ivertor and first wall armors (tiles) will be always exposed to high t emperature plasma of hydrogens. Therefore, heating tests should be imp osed on all new materials (PFM) developed for PFC as well as usual ero sion and recycling tests with hydrogens. Heating tests by electron bea m irradiation and thereafter by in situ plasma discharge in JT-60 were done on new composite ceramics made of boron carbide-carbon fibers wh ich were fabricated by hot-pressing in a vacuum at 2100 degrees C. It is shown that the composite ceramics containing carbon fibers in curle d plain fabrics (CFCPF) were not broken by the two kinds of heating te st, though a composite ceramics containing one dimensional or uni-dire ctional carbon fibers cracked in a heating test by electron beam irrad iation. The composite ceramics containing CFCPF could withstand 572 sh ots of in situ plasma discharge in JT-60 without cracking, where NBI ( neutral beam injection) heating was used with a maximum power of 30 MW for 1-2 s. Very small melted parts were locally formed near the edge of the tiles of the composite ceramics.