High heat flux tests on brazed divertor components in electron and ion beam test facilities

Abstract

Two different designs of single-tube metallic heat sinks with carbon armour tiles, designed by the Next European Torus (NET) team and manufactured by Metallwerk Plansee, were tested under thermal loading conditions simulating the normal operation parameters expected for the NET/ITER (International Thermonuclear Experimental Reactor) divertor. The experiments were performed in the Material Research Ion Beam Facility (MARION) and the Jülich Divertor Test Facility/Hot Cells (JUDITH), both at the Research Centre Jülich, and in the JAERI Electron Beam Irradiation Stand (JEBIS) at the Japan Atomic Energy Research Institute. The thermal response of the components was determined by stepwise increase of the heat flux, and the thermal fatigue behaviour was studied by cyclic loading at different heat flux levels. Additionall, finite elements analysis of the temperature and stress fields resulting from thermal loading was performed. No failure of the brazes resulted from exposing the component to a peak heat flux of 20·7 MW/m 2 in the screening test. In the thermal fatigue experiments, 300 cycles at 15 MW/m 2 were sustained in JEBIS, whereas in MARION, failure occurred after 376 cycles at 10 MW/m 2 surface heat flux. The results of the numerical analysis showed good agreement with the values measured in the experiments.