The first series-production inner vertical target (IVT) for the divertor of ITER, the international fusion experiment, has been completed in Germany by the manufacturer Research Instruments (RI), according to Europe’s ITER agency, Fusion for Energy (F4E), and the ITER Organization. The component is built to withstand heat loads of up to 20 MW/m² from the plasma.

The divertor sits at the bottom of ITER’s vacuum vessel and removes heat, helium ash and other impurities from the plasma, the ITER Organization explained in an October 19 update. F4E said it is made up of 54 cassettes arranged in a circle, with three plasma-facing targets mounted on each. Europe supplies the inner vertical targets, Japan the outer vertical targets and Russia the dome. According to ITER, these components must withstand heat loads of up to 20 MW/m², roughly 10 times what a spacecraft experiences when re-entering Earth’s atmosphere.

Each inner vertical target carries 2,208 precisely machined tungsten blocks, brazed to water-cooled tubes and mounted on a curved steel support structure. F4E said extensive tests had shown the units can withstand ITER’s environment, including high heat flux tests at HELCZA, a facility in Czechia funded by F4E, and reported that the results were “very positive.” The agency did not publish the test conditions or data in its announcement.

Pierre Gavila, a project manager at F4E, said the component “brings together many of the challenges found in fusion manufacturing,” including tight tolerances and complex joints. ITER said the unit is the product of more than a decade of development, prototyping and qualification, and that it was finished three years after series manufacturing began.

The work relied on a broad supply chain. ITER said fabrication involved more than 60 companies. F4E named Rolf Kind, ALMT, Yamato Gokin and PSFU as key suppliers to Research Instruments, with De Pretto Industrie in Italy providing the steel structure, and said more than 200 professionals from F4E, the ITER Organization, Research Instruments and its suppliers worked on the project.

Europe is responsible for 54 inner vertical targets plus four spares, or 58 in total. F4E said it tasked Research Instruments with 13 units in 2022 and later awarded it 15 more, bringing the company’s contracts to 28 units, while the French supplier ALSYMEX is working on 13. Michael Pekeler, managing director of Research Instruments, said: “To hand over the first series IVT to F4E for ITER is a major accomplishment for RI.” F4E director Marc Lachaise called the first IVT “made in Europe and manufactured in Germany” a “symbol of technological excellence.”

Why it matters

The divertor handles much of the heat and particle exhaust from ITER’s plasma, so its plasma-facing parts must survive extreme heat loads while staying within tight dimensional tolerances. Completing a first series unit marks the move from more than a decade of development, prototyping and qualification to series production for one of the machine’s most demanding components.

The milestone also shows how ITER spreads production across many firms and countries. More than 60 companies contributed to this one component type, two prime manufacturers in Germany and France share the European order, and other ITER members are building the outer targets and the dome. F4E said it and Research Instruments have worked together for more than a decade.

What to watch

The ITER Organization said the next challenge is to accelerate production while maintaining the quality standards the project requires. The announcements account for 41 of Europe’s 58 units, the 28 contracted to Research Instruments and the 13 being made by ALSYMEX, and do not say how the rest will be produced or when the targets will be installed in the machine.

The caveats

All of the information here comes from announcements by F4E and the ITER Organization, the bodies responsible for the component, rather than from independent reporting or a peer-reviewed publication. Neither announcement gives the cost of the units, their size or weight, or the detailed results of the heat flux tests.

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