Speaker
Karel Samec
(Centrum Výzkum ŘEŽ)
Description
The heat flux on plasma-facing components in ITER, and even more so in the projected DEMO reactor will reach values in the order of several Megawatt per square meter. Evacuating this heat in a reliable manner is key to the robustness and safety of operation of any fusion reactor.
The current state-of-the-art for cooling plasma-facing components relies on cooling a high heat-resistant structure using fluids. The wall and associated cooling tubes are usually an aggregate of different materials, which by virtue of their different thermal expansion coefficients, create differential elongation stresses at elevated temperature. In addition, heat diffusion through the thickness of the materials creates a thermal barrier. These effects limit the heat flux that may be evacuated reliably.
A design alternative is presented featuring a thin plasma-facing heat-resistant sheet wall which collects the heat from the plasma and rejects it to a structurally unconnected pipe forest behind the sheet wall which is at a far lower temperature. Heat exchange between the two components is through radiative heat exchange. Since the two components are structurally distinct, there is a greater freedom of choice in choosing the materials and no differential thermal stresses arise. A review of the possible designs and material choices is presented.
Co-author
Karel Samec
(Centrum Výzkum ŘEŽ, Husinec-Řež, Czech Republic)
