Three-Dimensional Thermomechanical Analysis of a Stainless Steel and Copper Divertor Plate for the Next European Torus

The performance and limits of a divertor plate for the Next European Torus (NET) are assessed. The design is a plasma-facing component that integrates the divertor plates and the inboard first wall in a monoblock panel. It is made of stainless steel poloidal U-tubes embedded in a copper matrix and protected by a carbon-fiber composite graphite armor. The thermal and thermomechanical behavior are analyzed in the high thermal flux zone taking into account the actual surface heating, which ranges from 5 to 10 MW/m². A simplified preliminary analysis assesses the water flow and the component geometry in accordance with the system and material data foreseen for NET. It is shown that if the surface temperature of the armor is limited to 1273 K, the graphite thickness must be limited to 7.5 mm. Detailed thermal and mechanical finite element analyses, performed by the CASTEM 2000 code, show that the cooling tubes remain just below the creep regime temperature. The allowable limits prescribed by international standards are met, and the component's lifetime is 3000 cycles.