On cold and crisp mornings, vapour can be seen rising from the ITER cooling cells. The tenuous plumes indicate that heat is being produced by the installation and evacuated by way of the heat rejection system. Since early September, the main contributors to heat production in ITER are the megawatt-class compressors in the cryoplant’s liquid helium plant. Twelve of them, out of a total 18, are presently at work compressing gaseous helium and feeding it to one of the cryoplant’s three cold boxes. Inside this giant refrigerator, the gas is processed and eventually liquified, ready to be distributed to components such as the tokamak’s superconducting coils and cryopumps that operate at a temperature of 4 K (minus 269 °C)—close to that of the interstellar void. Why produce helium at 4K now, when the ITER tokamak is not yet assembled? Because the highly complex machinery of the cryoplant, whose performance is absolutely crucial for ITER operation, needs to be tested in conditions that are as close as possible to future reality. The decision last year to build a cold test facility for the ITER coils1, which was not initially anticipated, has added a sense of urgency to the preparations. The facility’s final design has just been approved and commissioning is set to begin in July next year; the first actual cold tests are planned in late 2025. Like the operating tokamak, although in lesser quantities, the cold test facility will depend on a steady flux of liquid helium during its two to three years of activity2. Producing significant quantities of liquid helium is only the first step in demonstrating the full performance of this part of the cryoplant. Another important test is to mimic the loads that the tokamak’s magnetic system will exert on the liquid helium flux. “This is quite unusual in the world of large cryogenic facilities, where loads are generally stable,” explains Marie Cursan, a project engineer in the Cryogenic System Project. “In a tokamak, during a plasma discharge, the intensity of the load varies and follows an unusual shape that we need to adapt to.” The ongoing tests mimic the variations of the loads that the tokamak’s magnetic system will exert on the liquid helium flux. "This is quite unusual in the world of large cryogenic facilities, where loads are generally stable,” explains Marie Cursan, a project engineer in the Cryogenic System Project. One effect of these variations is the evaporation of small quantities of the liquid helium that circulates inside the magnets. Compensating this loss will require sophisticated instrumentation and automated systems designed to keep the fluid’s level constant. During commissioning, the role of the absent tokamak is played by a test cryostat, half-filled with liquid helium and located inside a cold box. Equipped with powerful electrical “heaters,” the device simulates the loads that plasma discharges and other events will generate. The test cryostat contains approximately 3,500 litres of liquid helium compared to the 200,000 litres (approximately 25 tonnes) that will be ultimately circulating inside the tokamak. Cryogenics are so central to future tokamak operation that commissioning the liquid helium plant involves several of the installation’s major plant systems. “You need to proceed hand in hand with the teams in charge of testing and operating the heat rejection and secondary cooling system, electrical distribution, site utilities, and overall operation coordination and management,” says David Grillot, the deputy head of the ITER Plant System Program. “It’s almost like operating a mini-ITER.” Pending the availability of the Control Building, cryoplant activities are managed from temporary control rooms staffed with ITER and Air Liquide staff. Tweaking and tuning the liquid helium plant’s machines and systems and bringing the totality of the compressors and cold boxes online will keep the ITER cryogenic team and Air Liquide experts busy onsite for approximately one year. And cryoplant activity does not end there. A second large power-class plant—which will produce3 liquid nitrogen at 80K for pre-cooling operations—has just entered the commissioning process with the recent start-up of the first two nitrogen centrifugal compressors. 1 Located in the partially vacated poloidal field coil winding facility, the coil cold test facility will accommodate D-shaped toroidal field coils and the smallest of the ring-shaped poloidal field coils, PF1 from Russia. 2 Another client for the cooling fluids produced by the cryoplant will be the cold testing installation for torus and cryostat cryopumps soon to enter the commissioning phase. 3 Pending the production on site of nitrogen extracted from air, ITER depends on daily deliveries by truck trailer.

Components installed in the ITER Tokamak Complex will be exposed to magnetic fields to varying degrees. To test the resistance of these components before operation, and to avoid the risk of dysfunction, samples are being subjected to maximum expected field levels in a test facility on site. How will the electronics planned for ITER react to magnetic fields? That is the question the Static Magnetic Field Test Facility has been installed to answer. With a maximum field of 275 mT and a test volume of one cubic metre, the facility is currently testing circuit breakers, electronic cards, valves and other components that will be installed near enough to the machine to experience some level of exposure. The electronics closest to the machine, located in the port cells, will be exposed to a field of approximately 200 milliTesla (mT), while instrumentation and control (I&C) cubicles and electrical distribution boards located in the Tokamak Building will face from 2.5 mT to 20 mT.  In a video filmed recently onsite, project leader Massimiliano Camuri shows off the facility and emphasizes the importance of the tests underway. "It is the only opportunity that we have to test in real conditions the equipment that later on will be installed in the tokamak." Watch the 3-minute video here.

Eighteen years ago, ITER, one of the largest research projects ever established, found a home in a small Provençal village—Saint-Paul-lez-Durance, pop. 956. A few years later, the ITER Organization moved into a building of its own, with a lobby large enough to welcome guests, host special events and … accommodate a tall Christmas tree. Presented by the municipality of Saint-Paul-les-Durance, its baubles and garlands lit jointly by the mayor of the village and the Director-General of the ITER Organization a few weeks before Christmas, the illuminated tree and the traditional crèche¹ at its foot have become a symbol of the relationship between the project, its staff and collaborators, and the local community of which they are now part. The illuminated tree has become a symbol of the relationship between the project and the local community of which it is part.  â€œThis great international scientific venture is now solidly anchored in our local territory, its culture and economy,” said Romain Buchaut, the mayor of the village, during his visit on Monday 2 December. ITER Director-General Pietro Barabaschi responded by drawing a parallel between the spirit of Christmas and that of ITER, both made of hope and expectations for renewal. 1 The crèche is an age-old popular representation of the Nativity, set in the context of traditional life in the villages of Provence with characters such as shepherds, a baker, a country priest, the Announcing Angel—all figured in clay figurines, or santons. The ITER crèche has innovated by including a fusion scientist.

The team operating the Korean tokamak KSTAR has announced it is running a new campaign of experiments focused on developing high-performance plasma scenarios. From now through February 2025, experiments will focus on: * achieving advanced plasma confinement under high-temperature, high-density, and high-current conditions * testing technologies for instability suppression * researching tungsten impurity control through tungsten divertor testing and in-depth wall studies In addition, the KSTAR team is planning over 40 collaborative experiments tackling fusion challenges with international partners, including research teams from DIII-D (USA) and WEST (France), and collaborators in Japan and China. These international partnerships will further expand to include the United Kingdom, the Czech Republic, and other nations in the future. See a full report on the Korea Institute of Fusion Energy website here.