Tore Supra experience on actively cooled high heat flux components

Abstract

Actively cooled Plasma Facing Components (PFCs) are one of the major issues of the next generation Tokamaks. Tore Supra is the only large Tokamak that has included actively cooled PFCs from the start up of the machine in 1988, with a continuous scheme of development to improve their performances and their reliability. The first generation of PFCs was designed to operate the machine under thermal equilibrium, with pulse length of 30 s. Their pioneering level of development, using graphite materials, led to some unreliability under heat loads. In addition, a number of physics mechanisms have been identified which led to tile damage and/or local destruction of the heat sink cooling structure resulting in three water leak events. The following generation, using CFC with an improved brazing technology including systematic inspection methods, had technological success. However, a few of these medium heat flux components (Inner First Wall, 2 MW/m 2) were also damaged during plasma operation due to unexpected local very high heat load deposition. Finally, the more recent development of PFCs concerns the actively cooled high heat flux finger element (up to 10 MW/m 2) devoted first to the RF antennae limiters and then to the Toroidal Pump Limiter (TPL) in the frame of the CIEL project. Although no negligible problems appeared during series fabrication, a large number (i.e. 800) of high performance pieces have been fabricated and its final delivery has been recently completed. First behaviour results obtained in 2001 during plasma operation with the Limiter start up version are also given.