Side view illustration of the Collective Thomson Scattering front-end design. The high-power probe beam is illustrated in purple, whereas the information gathered by the receivers is shown in dark blue.
ITER’s diagnostics will serve as the experts’ eyes into the machine. This vast network of high-tech systems will track many parameters to ensure the performance and safety of the fusion device. Europe is providing a range of these diagnostics, which come with complex specifications. Beyond the precision needed to monitor ITER’s core—using specialised techniques such as spectrometry or infrared imaging—these systems must fit seamlessly into ITER’s crowded port plugs and withstand radiation and other harsh conditions.
After years of design work to address these challenges, F4E’s teams and partners are seeing more diagnostics moving into production. This is now the case for the Collective Thomson Scattering (CTS) system. Last month, F4E signed a contract with IDOM and Sener to manufacture the first parts of this system.
The CTS will measure the fast ions speeding through the plasma, much like a radar. In particular, it will provide data on the density and velocity of the helium nuclei (alpha particles) produced by the fusion reaction. To do so, the CTS will launch a powerful microwave beam into the plasma. These waves are then scattered by the fast ions and collected by the CTS through receivers. By analysing the changes in the wave frequency, physicists can measure the fast ions. This insight into the fusion reaction will help them assess the experiment’s performance and model plasma scenarios.
The development of the CTS has been a thorough process. F4E, responsible for the front-end part, collaborated with the European laboratories DTU and IST and several companies to finalise its design. Building on previous sketches, the teams carried out extensive analysis to ensure it met ITER’s requirements, including performance, remote handling or structural integrity.
For the manufacturing phase, F4E opted for a phased strategy to minimise risks. In the first stage, IDOM will fabricate the simpler components while refining the design and processes for the more critical ones. These are, namely, the waveguides that will lead the microwaves to the plasma and the mirrors to deflect the radiation. The assembly of the mirrors with the cooling channels inside them is particularly complex and IDOM will have to qualify the delicate joining techniques to ensure everything fits perfectly
Immediately after that, F4E will launch stage two: the production of the mirrors and waveguides. “Despite the complexity, the robust design and our positive experience with the suppliers give us the confidence that we will manufacture successfully and complete the project on schedule,” claims Laura Sánchez, Project Manager at F4E.
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