In July 2020, in the middle of the exceptionally challenging Covid-19 pandemic, the ITER Organization marked the start of ITER machine assembly with a small ceremony on site. The cryostat base had been successfully lowered into place—the first in a succession of extraordinary lifting operations that would see the empty volume of the tokamak pit gradually transform into the ITER machine. Six years later, the ITER community gathered to celebrate another milestone in the making of ITER. With the arrival of the ninth and final vacuum vessel sector from Europe, all the components needed to complete the core* ITER machine are now on site. Standing in front of the massive component, delivered on Friday 2 October and still in its protective wrapping, ITER Director-General Pietro Barabaschi called it “a monument.”“Thanks to the effort that was made by our colleagues in the European Domestic Agency, Fusion for Energy, to complete this procurement program, the delivery of the last vacuum vessel sector will allow us to pursue machine assembly activities according to schedule,” he said. “Vacuum vessel sector #2 represents the last of our core tokamak components—now all toroidal field coils, poloidal field coils, correction coils, central solenoid magnets, vacuum vessel sectors and thermal shield sets are on site.”Fusion for Energy Director Marc Lachaise, who was able to connect remotely, said that the European vacuum vessel procurement program could only have been completed through close integration with the ITER Organization and other Domestic Agency partners. “This is an emotional moment for me and for others,” he said. “We can be proud of what we achieved.” “I am so grateful for the work you are doing, both here at ITER and in the Domestic Agencies of the Members,” the ITER Director-General told the crowd, celebrating the collaborative nature of every ITER milestone. "Thank you for a job well done." Europe worked for more than 16 years with the AMW consortium—Ansaldo Nucleare, Westinghouse and Walter Tosto—and a broader supply chain of at least 15 companies. Lachaise thanked Europe’s industrial partners and acknowledged the contribution of the Korean Domestic Agency, whose experience and lessons learned from manufacturing four of the nine sectors were shared with the European teams. All five European sectors were delivered to ITER over the past two years. The road to an assembled ITER machine is not over. In-vessel components, plant systems and other equipment are still to come, and much assembly work lies ahead. But one remarkable chapter has now closed. With all nine vacuum vessel sectors now on site, the major components needed to complete the core machine have converged at ITER after decades of development in ITER Member factories around the world. Piece by extraordinary piece, the ITER machine is coming together.*The core machine includes the cryostat, all superconducting magnets, and the vacuum vessel with its thermal shield. Not included in this description are in-vessel components like the divertor and the blanket. See this article on the Fusion for Energy website to learn more about the fabrication of five vacuum vessel sectors in Europe.

At the ITER Neutral Beam Test Facility in Padua, Italy, engineers have just taken delivery of the last two major components of MITICA—the full-scale prototype of ITER’s heating neutral beam injectors. The team is turning its attention to final assembly and commissioning. MITICA is one of two test beds at the Neutral Beam Test Facility established to develop and validate the technology for ITER’s powerful neutral beam injection system. On ITER, two heating neutral beam injectors will each deliver up to 16.5 MW of heating power to the plasma by accelerating negatively charged ions to an energy of 1 MeV, neutralizing them, and injecting the resulting high-energy particles into the plasma.SPIDER has been in operation since 2018 and is dedicated specifically to the production and extraction of negative ions. MITICA takes the development program a significant step further by reproducing the complete injector at full scale and full voltage.  The MITICA beam source at the Alsymex shop in Tarbes, France. Following delivery to Padua in June, the beam source underwent a series of site acceptance tests (visual inspection, dimensional checks, cooling circuit leak tests, and electrical and insulation tests). Some adjustments to ceramic-to-metal seals are also planned, incorporating experience gained from SPIDER, the other major test bed operating at the facility. ©ALSYMEX Inside the MITICA beam source, four pairs of radiofrequency drivers turn hydrogen or deuterium gas into a plasma. A specially treated grid extracts negatively charged ions out of the plasma, while a multistage accelerator accelerates them up to voltages approaching 1 million volts. The result is a beam of particles carrying up to 40 megawatts (MW) of power, making MITICA the most powerful ion source ever built.Its arrival in June 2026 at the Neutral Beam Test Facility was the culmination of a European procurement effort led by the European Domestic Agency Fusion for Energy (F4E), involving Research Instruments GmbH, Galvano-T, CECOM and 3DMF, with final assembly and testing performed by ALSYMEX in collaboration with F4E.At the opposite end of the MITICA beamline, the calorimeter will provide an essential diagnostic function during testing. Delivered by F4E and manufactured by the AVS-Tecnalia consortium, it is designed to intercept the full-power particle beam during commissioning and conditioning operations, allowing engineers to characterize its profile and intensity (reaching up to 14 MW/m²). The calorimeter consists of two movable panels equipped with closely spaced copper-alloy cooling tubes. While cooling water carries away the intense heat of the intercepted beam coming from the beam source, sensors embedded in the structure map out exactly how strong and how focused the beam is. ©RFX With the site acceptance testing of both components completed, final installation is scheduled to begin in spring 2027. In the meantime, work is progressing on another critical part of the test bed: the high-voltage power supply system. A fault in the 1 MV insulation transformer initially threatened to impact the program. Parallelizing activities and reorganizing the schedule has reduced the expected delay from approximately ten months to five.Repairs are now nearing completion, while testing of cryogenic cooling panels is also underway. The next major electrical milestone will be to bring the acceleration grid power supplies to their full 1 MV rating against a dummy load, demonstrating that the system is ready for the demanding conditions of beam operation.Commissioning of MITICA is planned to begin in summer 2027, opening a new phase at the ITER Neutral Beam Test Facility as the technologies destined for ITER’s two heating neutral beam injectors are tested and qualified at full scale.

International experts gathered at ITER for the Fourth IAEA Technical Meeting on Plasma Disruptions and their Mitigation to discuss advances in a field with implications for ITER and future fusion machines. Disruptions—the sudden and uncontrolled termination of a plasma pulse—are among the major challenges facing the operation of large tokamaks. Growing instabilities or a loss of plasma control can cause the plasma to lose its magnetic confinement and release stored thermal and magnetic energy on millisecond timescales. This usually leads to transient heat loads on plasma-facing components that are orders of magnitude higher than the stationary loads they normally handle, large electromagnetic forces on surrounding structures and, in some cases, beams of high-energy “runaway” electrons that may, in single events, severely damage plasma-facing components and can thus potentially lead to the interruption of operations. Such interruptions in a reactor-class device like ITER would be very costly.The lines of defence against disruptions are built around three key questions: How severe are the consequences of a disruption and can the machine withstand them? How accurately can a plasma disruption be predicted and what would be the proper response to avoid it? And when a disruption cannot be prevented, how can its consequences be mitigated?These are the central questions that brought together more than 60 specialists for the fourth edition of the International Atomic Energy Agency’s Technical Meeting on Plasma Disruptions and their Mitigation that was held at ITER last week. The topic has implications well beyond ITER and the ability to reliably avoid or mitigate disruptions will be increasingly important for future fusion machines, where high plasma energies and the need for sustained, reliable operation will place demanding requirements on plasma control and machine protection. ITER’s Stefan Jachmich is also concerned about disruption budget consumption: how plasma disruptions will affect component lifetime in the tokamak. For Stefan Jachmich, the ITER Science Division coordinating scientist for disruptions and the meeting host, one of the most encouraging developments since the previous edition in 2024 is the inclusion of machine-learning techniques in many aspects of disruption-related research. â€œFor instance, projections of what to expect are improving, including estimates of electromagnetic loads using synthetic diagnostics,” says Jachmich. “Reliable prediction is essential for both disruption avoidance and mitigation. A missed or late warning may leave too little time for an effective response while a false alarm can trigger an unnecessary shutdown and consume part of the machine’s disruption and component-lifetime budgets.”When a plasma disruption is predicted, avoidance measures can be taken through the plasma control system. Depending on the cause, the system can adjust the plasma’s magnetic configuration or use heating and current drive systems to suppress potentially disruptive instabilities.If a disruption is unavoidable, mitigation is required. ITER's mitigation system is based on shattered pellet injection. Pellets of cryogenic material (in the case of ITER protium and neon) will be accelerated towards the plasma and shattered before entering it. As the fragments evaporate in the plasma, they rapidly increase its density and help to dissipate a large fraction of its energy as radiation, reducing concentrated heat loads and the risk of runaway electron generation.While the overall design of ITER’s disruption mitigation system has already been established, important questions remain, including the optimal size and composition of the pellets to maximize the material assimilation and how best to deploy them under different plasma conditions. This gives the plasma disruption research presented at the IAEA technical meeting immediate relevance for ITER. Plasma disruption experts meet in the ITER Council Room. The technical meeting was organized around the themes of mitigation, prediction and avoidance, and consequences. Other concepts currently being investigated include dedicated runaway-electron mitigation coils and wave-driven pitch-angle scattering of runaway electrons. These approaches are not included in the present ITER design and would be applied to future fusion machines. Another important area of research is narrowing down the range of mitigation scenarios that ITER will need to test when Start of Research Operation begins. During this experimental phase, which is currently scheduled to start in late 2034, a temporary first wall will be in place. The plasma disruption team will be able to evaluate different prediction, avoidance, and mitigation techniques without fear of damaging the much more sophisticated, actively cooled wall that will be in place for deuterium-tritium operation. However, because each disruption provides only a single data point, modelling and multi-machine studies that combine results from other tokamak facilities at ITER Members’ fusion research institutes, along with other tokamaks that will commence operation in the coming years, are essential for precisely determining what ITER needs to test during the first phase.“For example, learning how to mitigate runaway-electron beams during the first phase of ITER operation with the temporary first wall is crucial,” says Jachmich. “This is where we need broad collaboration to build up a picture across different machines ahead of ITER switching on for the first time.”

Professor Raúl Sánchez assumes the direction of the Spanish centre of reference for magnetically confined plasma fusion studies. Physicist Raúl Sánchez has been appointed as director of CIEMAT’s Spanish National Fusion Laboratory (LNF). The Laboratorio Nacional de Fusión (LNF) is the Spanish centre of reference for magnetically confined plasma fusion studies and is member of the EUROfusion Consortium. Research at the LNF, on a European and international level, revolves both around the study of high-temperature confined plasmas, and research into the technologies such as materials, superconductors, tritium production, energy extraction, and remote maintenance needed to construct and operate fusion reactors.A professor at the Physics Department of Madrid’s Universidad Carlos III and an American Physical Society Fellow, Sánchez is also an ITER Scientist Fellow and one of the founding members of the group focused on pedestal confinement and stability modelling, created in 2016. His work focuses on the physics of plasma transport and magneto-hydrodynamic equilibria of fusion plasmas. Publications by G. F.-Torija Daza, et al., and J.M. Reynolds-Barredo, et al., are good examples of the work carried out under his leadership as ITER Scientist Fellow. Read more about the appointment of Raúl Sánchez as CIEMAT-LNF director in this article on the CIEMAT website (in Spanish). ITER Science Division head Alberto Loarte meeting with members of the Pedestal Confinement and Stability Group in February 2020. Outside of the coordination meetings planned at the ITER site, much of the work between ITER Scientist Fellows and ITER coordinators takes place by email and teleconference.