Development and Testing of the ITER Divertor Monoblock Braze Design

AbstractThe monoblock geometry is proposed for the ITER Physics Phase divertor for brazing of carbon armor tiles to copper or molybdenum cooling tubes. Elastic/plastic finite element analyses predicted high residual stresses except with OFHC copper. Samples of pyrolytic graphite tiles brazed to OFHC copper, Glidcop™ Al-15 copper alloy, and molybdenum tubing show cracking in all of the samples, except with the OFHC copper. A 3-tile divertor target consisting of 12 mm thick pyrolytic graphite brazed with a copper-silver alloy to a 12 mm diameter OFHC copper tubing was tested at 15 MW/m2 with a rastered 30 keV electron beam for 1000 thermal cycles. A gradual rise in surface temperature from 1000 C to 1200 C over the 1000 cycles was observed, along with hot stripes (1500 C) at the tile edges. However, no delamination cracks could be detected.

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