Heat flux pattern at grazing incidence in Tore Supra: Consequence of tile misalignment

Understanding heat flux deposition processes is essential for the design of the plasma facing components allowing reliable high power steady state plasma operations. Due to the magnetic configuration of Tore Supra, the deposited heat flux is found to be particularly sensitive to tile misalignment in a region where magnetic field lines graze the surface (incident angle typically <= 1 degrees). The experimental heat flux patterns deduced from IR imaging during high RF power operation (total injected power = 12 MW) are compared to the three-dimensional mapping of the toroidal pumped limiter surface provided by confocal microscopy measurements. A difference of altitude of 0.2 mm between two adjacent tiles can lead to a power deposition on the protruding tile up to 40% higher. The evaluation of the heat flux deposited on the leading edge, modelling of the hot spot and consequences for plasma facing components health and high RF power plasma operation are reported. (C) 2010 Elsevier B.V. All rights reserved.