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Development and Testing of the ITER Divertor Monoblock Braze Design

R.D. Watson, F.M. Hosking, M.F. Smith, C.D. Croessmann

Fusion Science and Technology / Volume 19 / Number 3P2B / May 1991 / Pages 1794-1798

Impurity Control and Plasma-Facing Component / Proceedings of the Ninth Topical Meeting on the Technology of Fusion Energy (Oak Brook, Illinois, October 7-11, 1990) / dx.doi.org/10.13182/FST91-A29603

The 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.