Design, fabrication and testing of an improved high heat flux element, experience feedback on steady state plasma facing components in Tore Supra

Actively cooled plasma facing components (PFC) have been developed and used in Tore Supra since 1985. One of the main technological problem is due to the expansion mismatch between graphite armour and metallic heat sink material. A first technology used graphite tiles with or without a reinforcement and a compliant layer, brazed with titanium copper-silver (TiCuAg) alloy. The next technology used carbon fiber material (CFC) tiles with a 2 mm pure copper compliant layer, since the good mechanical strength of the CFC allowed the reinforcement layer to be suppressed. No destructive inspection during the manufacturing procedure was found to be essential to insure a good reliability of the elements. A recent technology was developed for the new actively cooled toroidal pump limiter of Tore Supra (designed to remove up to 15 MW during 1000 s with incident heat flux up to 10 MW m(-2)). This new technology uses an active metal casting (AMC) of copper onto CFC tiles whose surface is prepared by a laser treatment. Copper compliant layer is then electron-beam welded to the heat sink. This technology is silver free and could be ITER relevant. The first bonding is X-ray controlled and the second one ultrasonic (US) tested. Finally all the elements are controlled by an infrared imaging technique during a hot water test. (C) 1998 Elsevier Science S.A. All rights reserved.