THERMOCYCLIC TESTS OF THE DIVERTOR PLATE MOCK-UPS FOR THE ITER REACTOR

The carbon-based materials CBM-copper, CBM-molybdenum and tungsten-copper types of joining are considered as reference design elements for the ITER reactor divertor plates. The results of the thermocyclic durability tests of the various types of mock-ups are presented. An electron beam facility with a total power of 60 kW was used as heat source. Two types of mock-up were tested. The testing of passively cooled mock-up was performed in regimes (q = 20 MW/m2, t = 0.3-0.5 s) simulating a steady state heat load of 10 MW/m2. The results have shown that brazing alloy Cu-Ga does not provide the sufficient durability resistance for CBM-Cu mock-up, for W-Cu joints the Cu-Mn-Fe-Ni-Si brazing alloy is most appropriate. Actively cooled W-Cu type mock-ups have been tested at q = 10 MW/m2, t(pulse) = 10 s. Visible damages (gaps, cracks) and changes in the temperature distribution after 2 x 10(3) cycles have not been found. The CBM-Mo monoblock type mock-ups have been tested at q = 10-15 MW/m2, those mock-ups survived for thermal cycles up to 10(2). Metallographic studies of the joints have been performed.