BRAZING OF THE TORE SUPRA ACTIVELY-COOLED PHASE-III LIMITER

The head of the water-cooled Tore Supra Phase III Limiter is a bank of 14 round OFHC copper tubes, curved to fit the plasma radius, onto which several hundred pyrolytic graphite (PG) tiles and a lesser number of carbon fiber composite tiles are brazed. The small allowable tolerances for fitting the tiles to the tubes and mating of compound curvatures made the brazing and fabrication extremely challenging. The paper describes the fabrication process with emphasis on the procedure for brazing. In the fixturing for vacuum furnace brazing, the tiles were each independently clamped to the tube with an elaborate set of ''window frame'' clamps. Braze quality was evaluated with transient heating tests. Some rebrazing was necessary.