Fusion reactors tested with materials designed for next-generation power plants
Two European tokamak facilities have completed the first comprehensive testing of tungsten components that will line commercial fusion reactors. The work demonstrates whether these materials can withstand the extreme heat and particle bombardment required for continuous operation—a critical engineering hurdle for the fusion power industry targeting deployment in the 2030s.
Originaltitel: Testing tungsten plasma facing components in WEST and AUG tokamaks
Abstract Next step fusion devices will face unprecedented heat loads and particle fluence with thousands of hours of plasma exposure on plasma-facing components (PFC) cumulated over the entire lifetime of the device. These components must guarantee acceptable lifetime, reliable heat exhaust capabilities (10-15 MW/m2 power fluxes in steady state) and a high level of resilience after multiple thermal stresses generated by combined steady-state heat loads and transient events, such as ELMs or disruptions. An extensive tungsten (W) PFC testing work-program has been conducted in the WEST (Tungsten Environment in Steady State Tokamak) and ASDEX Upgrade (AUG) tokamaks, taking advantage of key capabilities and strengths of the two machines. WEST is a superconducting tokamak with long pulse duration capabilities currently equipped with an ITER-grade actively cooled divertor, including shaped monoblocks (MB) with the 0.5 mm height toroidal bevel as foreseen for ITER, while AUG allows the exposure of dedicated tile-sized samples (with different geometries, gap size, slopes and materials) in ELMy H-mode discharges using its divertor manipulator DIM-II system. The first part of the paper reports on the operation of the ITER-grade PFC in WEST since the commissioning of the divertor in 2022. The second part of the paper presents dedicated experiments performed in AUG and WEST in order to study W failure modes, W melting across toroidal gaps (during sustained or transient melting) and impact of the runaway electrons on W material. The results reported here provide new information on W material response (e.g. heating, cracking or melting) of direct relevance to ITER.