Following 15 years of hosting the design and construction of the world’s largest superconducting magnet, last week the Magnet Technology Center near San Diego, California, became an auditorium and exhibit space to celebrate the completion of the ITER central solenoid. United States Congressman Scott Peters and Mayor of San Diego Todd Gloria were on hand to headline the ceremony, together with Neal Blue, the proud CEO and Chairman of General Atomics, and many other dignitaries. Video tributes poured in from multiple US senators and representatives, as well as from members of the California State Congress. Throughout the event, a central theme echoed: local pride at being part of the ITER global fusion initiative, coupled with determination to build San Diego into a national and global hub for fusion R&D. The central solenoid, when completed, will weigh 1,000 tonnes and be roughly the height of a five-story building, with a stored magnetic energy of 6.4 gigajoules and a maximum field of 13 tesla. Positioned along the central axis of the ITER tokamak, it will enable a powerful pulsed current of 15 megaamperes to be induced in the plasma for 300-500 seconds. The central solenoid will work in conjunction with the poloidal field magnets to control and shape the fusion plasma.General Atomics has constructed the central solenoid in six independent coil packs, plus a spare seventh module, wound from niobium-tin superconducting cable produced in Japan. One by one, these modules have been tested, packed, and shipped to ITER. Five have arrived so far; the sixth was completed in April and is en route, while the seventh took its place as an impressive backdrop for the celebration (see photos).“The central solenoid is unlike anything that has ever been built,” was the characterization given by Nikolai Norausky, program manager of the central solenoid project at General Atomics. “We’re talking about orders of magnitude of scale. We had to develop a modern supply chain. Often our suppliers were dealing with the largest, or the heaviest, or the most precise aspects of their technologies. And we had to bring all that in to develop the manufacturing know-how, and the tooling, in order to produce the central solenoid magnets.” In July, the US Congress passed an official resolution recognizing the completion of the ITER central solenoid. During the completion ceremony at the end of August, US Representative Scott Peters (right) presented a copy of the Congressional Record to Neal Blue, CEO and Chairman of General Atomics. For many years, General Atomics has been a leader in nuclear research in fields ranging from electromagnetics to the production of the precisely shaped fuel targets used in inertial confinement fusion. General Atomics operates the DIII-D tokamak—the largest fusion facility in the United States—on behalf of the US Department of Energy. The company is also producing several plasma diagnostics for ITER. Now that central solenoid manufacturing is completed, the magnet technology hall where the modules were produced will be converted into a blanket test facility.In his congratulatory remarks, Congressman Peters noted that he, together with Mayor Gloria and a sizable San Diego delegation, will be taking part in a trade mission to France in September, where they plan to visit the ITER worksite. The highlight, of course, will be to see the central solenoid modules being stacked in the ITER Assembly Hall, in the next stage of the component's journey.Read the General Atomics press release here.

Teams onsite have completed the installation of the first ITER gyrotron and commissioning tests will start later this month. The microwave-generating device, supplied by Japan, is the first of 24 gyrotrons to be installed on the top floor of the Radiofrequency Building and one of 72 gyrotrons overall that will be needed when scientists introduce tritium for the first time into the ITER device (a scientific phase called DT-1). Referred to as "plasma starters" for their role in initiating plasma pulses or "wave generators" for their efficiency at generating high-frequency waves to match the resonant frequency of electrons in the plasma (170 GHz), gyrotrons are a critical part of auxiliary heating at ITER. Electron cyclotron resonance heating (ECRH) heats the electrons in the plasma; the electrons in turn transfer the absorbed energy to the ions by collision.The original baseline plan for ITER called for 24 gyrotron devices (8 from Japan, 8 from Russia, 6 from Europe and 2 from India). The first sixteen from Japan and Russia have passed all factory acceptance testing and been delivered to ITER. One by one, teams will install them in the Radiofrequency Building's "gyrotron floor" (level 3).The new baseline, which demands more powerful radiowave plasma heating, has modified plans both for gyrotron procurement and for the Radiofrequency Building. Forty-eight gyrotrons will now be required at the start of ITER operation and another 24 for the first phase of deuterium-tritium plasma operation (DT-1). This requires additional procurement, an annex to the Radiofrequency Building, and an entirely separate building for equipment for the ion cyclotron resonance heating system.In a milestone for the radiofrequency heating program, the installation of the first gyrotron procured by the Japanese Domestic Agency is now complete. It has been connected to its power supply and commissioning is forecast to begin later this month. One of the highlights of commissioning will be the generation of the first radiofrequency waves.

Forty-four power converter units are tasked with “stepping down” and converting the AC voltage arriving from the ITER switchyard to the precise voltages required by the individual magnet systems. Outside of the Magnet Power Conversion buildings, 32 units procured by China and Korea under Procurement Arrangements are already undergoing commissioning. Major Task Agreements for the remaining systems were signed this summer. Outside of the Magnet Power Conversion buildings on the ITER site, power converter transformers installed in individual bays bring down the voltage received from the switchyard to lower voltage levels required by the ITER magnet systems. Inside the building, each unit is paired with a large rectifier whose function is to convert AC voltage to DC voltage; once the voltage has been "rectified," it can be fed to individual magnet systems through steel-jacketed aluminium busbars. Thirty-two converter units are already in place, but the coil power converter system requires 12 more before the machine can turn on for the Start of Research Operation (SRO).  A significant milestone for the coil power converter system was reached this summer with the signature of two Task Agreements for this complement of equipment.  Double screen: on 19 August 2025 the ITER Organization and the Chinese Domestic Agency signed a Task Agreement for stage 2 poloidal field, vertical stability power converters and DC interconnecting busbars. On 19 June, the ITER Organization and the Korean Domestic Agency signed a Task Agreement for six units of central solenoid AC/DC power converters and the upgrade of the master control system for the integration of stage 1 and stage 2 systems. The equipment will be manufactured by Dawonsys Co. Ltd, the company that already supplied 18 power supply units and the master control system (stage 1). The scope of the Task Agreement includes design, prototyping, manufacturing, integrated testing, and on-site commissioning of the stage 2 systems.Two months later, on 19 August, the ITER Organization signed a Task Agreement with the Chinese Domestic Agency for two units of poloidal field AC/DC power converters, four sets of vertical stability coil AC/DC power converters, and the DC interconnecting busbars that will link stage 1 and stage 2 converters. The equipment will be manufactured by a consortium led by the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), and that includes the Southwest Institute of Nuclear Physics, Rongxin Huike Electric Co., Ltd., China Nuclear Power Engineering Co., Ltd., and China Nuclear Industry 23 Construction Co., Ltd. Task Agreement scope includes the design, prototyping, manufacturing, integrated testing, and on-site commissioning of these systems. The Task Agreements for stage 2 main coil power converters were concluded six months ahead of schedule, reflecting a strong level of collaboration between the ITER Organization, the Domestic Agencies, and industrial partners and demonstrating the commitment of stakeholders to achieving the ITER 2024 Baseline. 

After working with a domestic manufacturer to qualify a first outer vertical target for the ITER divertor in 2024, Japan's National Institutes for Quantum and Radiological Science and Technology (QST) successfully worked with a second manufacturer, Hitachi Ltd., to develop and qualify a second full-scale mockup of this critical plasma-facing component. The divertor targets—the dome (produced by Russia), the inner vertical target (produced by Europe) and the outer vertical target produced in Japan—face the highest head loads of the ITER machine. The divertor is one of the most important components in a tokamak, as it plays a role in maintaining the stability of the nuclear fusion reaction by exhausting impurities such as fuel residue and helium. The divertor must be designed to withstand direct heat and particle load from the plasma. The armour material, tungsten, has been chosen for its high melting point, but the shape of the plasma-facing surfaces is also important. High precision machining and assembly technologies are required to achieve the correct overall shape, inclination, steps and gaps within tolerances of 0.5 mm or less.The heat load on divertor targets can reach 20 MW per square metre—equivalent to the surface heat load that an asteroid probe is exposed to when re-entering the atmosphere and much higher than the surface heat load sustained by the Space Shuttle. The divertor outer vertical target prototype produced by Hitachi Ltd. in collaboration with Japan's National Institutes for Quantum and Radiological Science and Technology (QST). Beginning in 2022, Hitachi and QST began developing a second full-scale outer vertical target markup. Hitachi called upon its experience in the nuclear field, employing the high-quality welding technology for special materials and non-destructive inspection technology developed for restricted and complex shapes to achieve the high-precision machining and assembly required by ITER. The prototype was completed in March 2025 and in July, a high-heat-load sample of an outer vertical target passed the rigorous certification test demanded by the ITER Organization.In total, QST is responsible for delivering 58 outer vertical targets to the ITER Organization.Read the QST press release dated July 2025 in Japanese or English. 

The ITER Organization was one of the sponsors of the 55th International Physics Olympiad (IPhO), held in Paris from 18 to 24 July 2025.  Each year, the International Physics Olympiad unites the world’s brightest secondary school students for demanding physics competitions alongside a rich program of cultural and scientific activities that foster international dialogue and collaboration. Open to students under the age of 20 who have not yet entered university, the IPhO aims to challenge participants’ knowledge, analytical and critical thinking, problem-solving skills, and mastery of both theoretical and experimental physics. This year, more than 400 candidates from 87 countries took part in the prestigious event.In its role as sponsor, the ITER Organization assisted the scientific committee in developing the problems for the Olympiad’s two five-hour exams—one theoretical and one experimental. Sven Korving, a Postdoctoral Researcher with ITER’s Plasma Modelling & Analysis Section, took part in this work and later joined the event in Paris, where he presented the ITER diversity award celebrating the growing diversity of the physics community—both in terms of gender and geographic representation. Sven Korving, Postdoctoral Researcher at ITER (3d from left) presents an award for diversity to the national team of Turkmenistan.

Fusion Power Associates (FPA), the US-based non-profit that has been advocating for the development of fusion energy since its founding in 1979, is making a few changes. In a letter to FPA members and the broader fusion community, the organization announced that its longtime president and co-founder Stephen O. Dean would be transitioning to the role of President Emeritus and that the organization would be moving from the Washington DC area to be hosted by the University of California San Diego (UC San Diego). Michael Campbell and Farhat Beg, respectively Professor of Practice and Professor in the Mechanical and Aerospace Engineering Department at the university, will be taking over as Fusion Power Associates President and Senior Vice President.Recent developments are contributing to a growing fusion ecosystem in the San Diego area. General Atomics, which operates the DIII-D tokamak for the US Department of Energy and also fabricates target assemblies for inertial fusion, is located just north of the city. (See the story on the completion at General Atomics of the ITER central solenoid is this issue of the ITER Newsline.) The company announced in March that it was collaborating with UCSD on a Fusion Data Science and Digital Engineering Center as part of efforts to fast-track fusion energy development; it is also part of a new research collaborative focused on developing and scaling up inertial fusion power facilities. And at UCSD, a Fusion Engineering Institute was launched last year to focus on some of the engineering challenges that must be addressed for commercially attractive fusion. With a large San Diego delegation planning to visit ITER later this month, we expect to hear more about emerging plans to position San Diego as a fusion R&D hub.

The 2024 ITER Organization Report on Human Resources has just been published.Follow this link to browse through the report, which offers insight into the human dimension of the ITER Organization through statistics on staffing trends, recruitment, mobility, development, performance, remuneration, and more. It also highlights the growing diversity of the organization—both in terms of professional roles and also in terms of the backgrounds and profiles of ITER staff and their families, who come from more than 30 countries.To learn even more about what it is like to work at the ITER Organization, see this selection of staff stories. See all ITER Organization reports on the Publications page of the website.