Europe ready to light up blazing fire of negative ions
Unlike most fires that we fight to put out, this is one that engineers have been working hard to start. It will be essential to the success of ITER so as to raise the temperature of the super-hot plasma to approximately 150 million °C. Basically, beams will need to be powerful enough to help individual particles reach the core of the hot gas quickly. This is why F4E in collaboration with Alsymex, through a multi-million contract, have been working on the beam source that will fire ions at an energy of 1 MeV.
This technology will be first tried at MITICA (Megavolt ITER Injector and Concept Advancement), located in Padua (Italy), where the ITER Parties of Europe, Japan, ITER Organization, and Consorzio RFX, will test a full-scale prototype of the Neutral Beam Injector (NBI) that is aimed at generating a power of 16.5 MW. Based on its performance, and lessons learned, two of them will be produced to be used in the ITER device.
The MITICA beam source consists of two main parts: a radio frequency ion source and an accelerator of seven grids. The beam source will measure 3 x 3 x 4.5 m and will weigh in total 15 T. To complicate matters, the specifications of this cutting-edge equipment are demanding and need to comply with strict mechanical tolerances. When the beam source is installed in the vessel, it will rely on a handling tool to slide on its rails where it will be fixed.
In 2019, work started with the engineering design review to prepare documentation and to complete the manufacturing design of all components, sub-assemblies and tooling. Next, the engineers developed the prototypes, which had to be tested to pave the way for manufacturing. In 2021, approximately 75% of manufacturing activities and sub-assembly of components were completed. The forecast for this year is that production will come to an end together with the assembly of the accelerator, ion source and all auxiliary equipment. By mid-2023, following the successful execution of factory acceptance tests, the beam source will be delivered to Padua, where it will join the rest of the MITICA components.
More than 20 European companies from Germany, Netherlands, Italy, France are contributing to the beam source. Ultimately, the components are gathered under one roof at the ALSYMEX factory in Tarbes, France. In this hub, the pieces are carefully assembled. Nearly 250 km away, in the city of Bordeaux, at another workshop of Alsymex, the remote handling tool has been undergoing factory acceptance tests using a mock-up of the beam source. Speed, positioning, and loading, were successfully measured ranging from no load to 20 T.
F4E’s Project Manager, Antonio Masiello, working with a team of experts, explains the process: “For the award of this tender we used a more dynamic approach to agree on the final specifications. We engaged through a framework contract with different suppliers who performed a design revision of the beam source. They were asked to go into detail about the requirements and confirm their technical capability to deliver the design or propose changes to it. In the end, suppliers had to endorse their final design and provide a final offer honouring all agreed requirements. This was a new way of working together towards a mutually accepted design, minimising risks during the execution of the contract. Looking back, it may have taken us longer, but it was much more efficient in the long run. Today, we have completed 90% of production in spite of the additional difficulties we faced during the pandemic.”
The transition from design to components is impressive. When we visited the factory in Tarbes, we were able to see the three stagesof the accelerator already assembled. Each part, weighing 2 T, is mounted on an assembly structure, and then tilted by 90 ° to verify that all 1280 apertures are aligned to those of the other grids.
We spoke to Dominique Guénot, Alsymex Programme Manager, to hear more about their contribution. “The MITICA beam source is an exciting but very challenging project. We confirm that most of the technical risks have been removed. The accelerating grids and source case lateral walls have been delivered, complying with the demanding specifications, by our partners Research Instruments, Galvano T and Cecom. Moreover, we have proven our skills to perform precise assembly and adjustments on the first two stages of the accelerator. Alsymex is proud of the results achieved so far and extremely pleased with the fruitful collaboration with the F4E, RFX, and ITER Organization teams. Our aim is to deliver the beam source to Padua in 2023.”