The generations of physicists, engineers, technicians and other specialists who have worked in nuclear fusion share a common goal, dedication and responsibility: making nuclear fusion possible for the next generations. While grappling with unsolved issues can make a career in fusion feel a little bit like Ulysses' long and difficult journey in Homer's Odyssey, the large international team working on the disruption mitigation system for ITER has now completed a major milestone in its journey. During the final design review held in late March at ITER Headquarters under the chairmanship of George Sips (General Atomics, San Diego), no showstoppers were identified and the disruption mitigation system (DMS) for ITER has been greenlit to continue its path towards manufacturing, installation and operation. As part of the review, the teams working together on the design and physics of the disruption mitigation system and diagnostics port integration, along with many international collaborators, introduced to the review panel a subset of the system's complete technical documentation, amounting to over 30,000 pages of design descriptions, diagrams, engineering analyses, calculation reports, and prototype test reports. Over four days the full detailed design of the disruption mitigation system of ITER, comprising more than 100,000 components, was presented in person in the ITER Council Room and via video conference in 40 concise presentations by 33 presenters. More than 100 internal and external technical experts were invited to review the detailed design of this crucial ITER machine protection system. The disruption mitigation system will protect machine components against excessive heat loads and electromagnetic forces that result from plasma disruptions, which cause a sudden loss of stored thermal and magnetic energy. The disruption mitigation system will use shattered pellet injection to deliver massive amounts of protium and neon in the form of small ice fragments into the plasma to convert the energy into radiation. The rendered computer model shows an ITER vacuum vessel sector on the right with the disruption mitigation system injectors and supporting hardware at equatorial and upper port levels. Other injectors and associated hardware are shown in the model in orange and grey. The small human figure (if you can spot it) gives an idea of the scale. In 2017, a workshop with worldwide plasma disruption experts was held in the exact same room as the final design review. The verdict was clear: due to the complex nature of disruptions, significant gaps existed in the physics understanding which had to be addressed. One year later, in 2018, the ITER Science and Technology Advisory Committee concluded that plasma disruptions posed an existential threat to the ITER mission and that their mitigation was of the highest priority. The ITER Council instructed the ITER Organization to set up project teams to develop the required physics basis and to design an efficient disruption mitigation system for the project. To understand why the worldwide experts are worried about the fast accidental losses of plasma current and stored energy that occur during disruptions, one only has to keep in mind that the stored magnetic energy in ITER can reach about 1 GJ, and it would be released within a fraction of a second. This is equivalent to the kinetic energy of a 100-tonne railroad locomotive travelling at about 500 km/h as it impacts a massive wall. While most parts of the ITER machine like the vacuum vessel are designed to withstand any possible disruption event, it is still important to protect the components inside the machine from excessive electromagnetic loads. Although armoured with tungsten, which has the highest melting point of all known elements (3422 °C), the components facing the fusion plasma can be subject to melting from heat loads and the impact of so-called runaway electrons. If such damage were to occur, plasma operation would have to be halted for long periods of repair, moving ITER's goal of demonstrating the feasibility of fusion further into the future. To cope with these potentially damaging effects, an international scientific and engineering team has developed a sophisticated and robust mitigation method that can protect the ITER machine by reacting within milliseconds, similar to the way an airbag is deployed in a car. The final design review of the ITER disruption mitigation system took place from 26 to 29 March 2024. More than 100 experts participated in person or on line. The ITER disruption mitigation system is based on shattered pellet injection. Wine-cork-sized hydrogen and neon pellets formed in what is called a cold cell assembly (see gallery below)—at the cryogenic temperature of -268 °C and in an ultra-high vacuum environment—are released by a specially developed electromagnetic valve opening within 1-2 milliseconds of the start of a disruption. The pellets are then accelerated to supersonic speeds (> 1800 km/h) and fly with an exceptionally accurate trajectory (with just 5 mm clearance between the pellet and the wall on either side) through a narrow flight channel over a distance of six metres. At the end of its path each pellet deliberately collides with an inclined surface and is shattered into thousands of small broken pellet fragments, which will enter the plasma and mitigate the disruption. By the time these pellet fragments arrived in the plasma, about 12 milliseconds will have passed since the system was activated which is about ten times shorter than a blink of an eye. For the last six years a large international effort—involving science and engineering teams under DMS Task Force Leader Michael Lehnen and Technology Group Leader Stefan Jachmich; the ITER disruption mitigation design team; disruption mitigation experiments and accompanying simulation efforts (read more here and here); and countless technical meetings (see reports here and here)—has built not only a solid knowledge basis in terms of physics and technology, but has led to the development of technologically advanced design solutions that work reliably in cramped space and in one of the most extreme environments on the planet. More hurdles remain ahead before the disruption mitigation system can demonstrate its capability to protect the ITER machine against the detrimental consequences of disruptions and ensure that ITER will reach its final goal. But judging from the challenges already overcome by the ITER and international teams we are confident that we will get there ... one step at a time.

A public event on Saturday 13 April draws a big crowd. It was a beautiful, summer-like day on Saturday 13 April. Perfect for a journey into ITER. Nearly 800 members of the public, were welcomed on site by an all-volunteer roster of guides, timekeepers, hosts and hostesses, plasmagicians and specialists of all kinds. Younger people have the advantage! They get to work their way right up to the plexiglass that separates the port cell corridor from the impressive Tokamak pit. You can almost imagine the plasma whizzing around the central column. It's a regular occurance at ITER. Twice a year since 2011, in spring and autumn (with only one notable year excepted) the gates open to visitors of all ages who have been lucky enough to secure a spot. Curiousity in the region about ITER is understandably high—after all, the tallest buildings are visible to all who drive north to the French Alpes. Open Doors Days are one way to share ITER with the public; the ITER visits team also runs a program that welcomes individuals and small groups throughout the year. (Just over 25,000 people visited ITER in all last year; since 2007 the figure tops 200,000). For those who were not able to make it this time, another Open Doors Day event is planned in November 2024. See the gallery below for some of the scenes from the day. Or watch "Having fun while discovering ITER" on YouTube.

Contrary to the vast majority of ITER machine components, the modules that form the central solenoid cannot be lifted by way of hooks and attachments. The 110-tonne cylindrical components provide no space for a robust structure for the bolting or welding of lift devices; instead, a central solenoid module needs to be handled like one would grasp a giant bowl of cereal, by exerting pressure from the outside. A bowl of cereal can be grasped and moved with two hands. A central solenoid module requires nine powerful wedge pads located at the bottom of a lifting fixture, each one exerting a radial force of 220 kN (equivalent to 22 tf (tonne-force)) on nine friction pads distributed around the cylinder. Designed and manufactured by US ITER, who procures the central solenoid, the system has once again proved its efficiency. On Thursday 11 April, the third module was successfully lifted and positioned with a slight radial offset on top of the existing two-module stack. The 325-millimetre offset provides room for equipment and connection work to be completed before the module gets positioned in its final location, aligned on the central solenoid axis. Almost there. In a few moments, the third module will be positioned on top of the existing two-module stack, with a slight radial offset to provide room for equipment and connection work.

The 13th ITER International School (IIS) will be held from 9 to 13 December in Nagoya hosted by National Institute for Fusion Science (NIFS), Japan. The subject of the 2024 school is "Magnetic fusion diagnostics and data science," with a scientific program coordinated by Profs. M. Yokoyama and K. Tanaka (National Institute for Fusion Science) and Drs. M. Kocan and S. McIntosh (ITER Organization). Diagnostics are key to the achievement of ITER fusion power demonstration goals and they require the application of a wide range of techniques. But diagnostics are not enough to ensure ITER's success; only through the advanced analysis of the data they provide will it be possible to guide the experiments towards their fusion power goals. It is timely to address these multidisciplinary areas during the 13th ITER International School. The ITER International School aims to prepare young scientists and engineers for working in the field of nuclear fusion and in research applications associated with the ITER Project. The adoption of a "school" format was a consequence of the need to prepare future scientists and engineers on a range of different subjects and to provide them with a wide overview of the interdisciplinary skills required by ITER. The next ITER International School will take place in Nagoya, Japan, hosted by the National Institute for Fusion Science (NIFS).

The annual PhD Event organized by the European Fusion Education Network, FuseNet, will take place this year at the University of Stuttgart, Germany, from 3 to 5 September.Meet and greet fellow fusion researchers from Europe and expand your network. The event will feature high-profile keynote speakers, a top-notch scientific program and the much anticipate PechaKucha contest, where students present their research in 20 slides, 20 seconds per slide. Registration is open through 15 June 2024. See more information at this address.