Divertor inner target
Europe launches manufacturing
Fifty-eight inner vertical targets—one for every divertor cassette body (54) plus four spares—will be manufactured under the procurement responsibility of the European Domestic Agency. Positioned at the intersection of magnetic field lines at the bottom of the ITER machine where particle bombardment is particularly intense, these challenging components have undergone a lengthy manufacturing qualification phase. Now, the German firm Research Instruments has been awarded a contract for the first series of 13.
The plasma-facing components of the ITER divertor—the inner vertical target (Europe), the outer vertical target (Japan), and the dome (Russia)—will be exposed to a heat load that is ten times higher than that of a spacecraft re-entering Earth's atmosphere (10-20 MWm²).
An inner vertical target prototype produced by Research Instruments. Each target weighs approximately 0.5 tonnes and measures 1.5 metres in length. On the curved steel support structure are 1,104 tungsten monoblocks that are actively cooled by pressurized water.
Tungsten, a shiny, silvery-white refractory metal that has a high melting temperature (3400 °C), will armour these plasma-facing components. For the inner vertical target, the maximum expected temperature on the tungsten surface will be about 1000 °C in normal operating conditions and 2000 °C in off-normal conditions.
During a lengthy manufacturing qualification program, the European Domestic Agency, Fusion for Energy, worked with a number of suppliers to ensure competition and mitigate technical risks through the development of different technologies. After the successful fabrication and testing of small-scale (~1/20th) tungsten monoblock mockups mounted around cooling channel, three companies—the AES Consortium (Ansaldo Nucleare, Ansaldo Energia, and SIMIC), Alsymex, and Research Instruments—were able to qualify full-scale prototypes. Among the most difficult challenges encountered were the procurement of tungsten monoblocks, the bonding of the monoblocks to the copper alloy cooling tubes, the fabrication of the steel support structure, and strict dimensional requirements.
In a major milestone that heralds the start of manufacturing, a first contract has been signed with Research Instruments for the production of 13 inner vertical targets.
See the full story on the Fusion for Energy website.
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