Call it magic, or call it a happy coincidence: the temperature of liquid helium (minus 269 °C) is precisely that which is required to achieve superconductivity in niobium-tin and niobium-titanium alloys. Such a temperature is indeed very, very cold—absolute zero (minus 273.15 °C), the lowest possible temperature, is only a few degrees colder. The second most abundant element in the Universe and also the second lightest, helium was first identified in the spectrum of the Sun in 1878, hence its name which derives from Helios, the ancient Greek personification of the Sun.   Used in cryogenics, arc welding and the silicon wafer industry—as well as for party balloons and airships—helium is extracted directly from natural gas. It is produced mainly in the US, Qatar and Algeria.   In ITER, huge volumes (approximately 25 tonnes) of liquid helium will be circulated throughout a complex, five-kilometre-long network of pipes, pumps and valves to keep the 10,000-tonne magnet system at superconducting temperature.   Helium will also be required to provide cooling power to the thermal shields, which reduce the large temperature gradient between the superconducting magnets and the tokamak environment, and the cryopumps that use extreme cold to achieve high vacuum in the plasma chamber.   On the ITER platform, work is progressing on the foundations of the soccer field-size building that will accommodate the cryoplant. The completed building structure should be delivered in April 2017. © ENGAGE As a consequence, the ITER cryoplant—three coupled units that will provide cooling fluids to the whole installation—will be the largest in the world, with 75 MW of combined cooling power (1).   Liquid helium will be delivered to ITER in 40-cubic-metre containers. (In a prowess of insulation technology, the -269 °C temperatures will be maintained throughout the 45-day-long journey from the production site to the ITER cryoplant. About seven container loads will be needed to fill the entire helium cooling circuit of the ITER installation.   The complexity of the cooling processes, along with the flux rate required for the cooling of magnets, cryopumps and thermal shield, has dictated the size and design of the cryoplant.   The soccer field-size installation will comprise three identical liquid helium plants—the best solution in terms of technology, economy and risk. Each plant will rely on six powerful megawatt-class screw-compressors, four high-speed turbines and ten aluminium-brazed heat exchangers assembled in 20-metre-long vacuum-insulated "cold boxes."   At the Air Liquide workshop outside of Grenoble, France, workers are in the process of equipping the cold boxes with their internal components. (During a visit to the factory last summer, French President François Hollande autographed one of them.)   Operating the cryoplant will require 35 MW of electrical power—comparable to the needs of a European town with a population of approximately 45,000. The cryoplant will operate non-stop but will only deliver its maximum cooling power during plasma discharges.   Helium is not the only ultra-cold fluid that the cryoplant will produce. Liquid nitrogen, at a temperature of minus 196 °C, will be used as a "pre-cooler" in the liquid helium plants.   Nitrogen, which accounts for approximately 78 percent of the air we breathe, will be extracted directly from the atmosphere in an on-site gaseous nitrogen generator with a production capacity of 50 tons per day and then processed in two large liquid nitrogen plants.   Magnets are the main consumers of cryogenic power (45 percent), followed by the thermal shield (40 percent) and the cryopumps (15 percent). But of the total cryogenic power delivered by the cryoplant, only 75 percent will actually cool the machine components—the remaining 25 percent of the nominal 75 kW will be needed to compensate the warming of the fluid due to the rotating pumps and, to a much lesser extent, the thermal losses in the five-kilometre long cryodistribution network.   The cryoplant's "cold boxes" are currently being equipped with internal components at the Air Liquide factory in Sassenage, near Grenoble, France. During a visit to the factory last summer, French President François Hollande autographed one of them. However sophisticated the technology implemented, leaks will occur. Based on experience at CERN, where helium is also used to cool the superconducting magnets in the giant accelerator, ITER experts consider that between 10 to 20 percent of the total helium inventory will be lost in the course of one year, mainly during maintenance phases. Although some of the helium will be recovered, an average of one 40-cubic-metre container per year will be necessary to compensate the losses.   Three parties are associated in the procurement of the ITER cryoplant: Europe (the liquid nitrogen facility and auxiliary systems), India (the interconnecting lines and cryodistribution equipment), and the ITER Organization (responsible for the direct procurement of the liquid helium plant). The design of the cryoplant was finalized in 2015 and manufacturing will be complete by the end of 2016.   On the ITER platform, work is progressing on the foundations of the building that will accommodate the cryoplant. The completed building structure should be delivered in April 2017.   (1) The Large Hadron Collider (LHC), at CERN, achieves a cooling power of 144 kW at 4.5 K with several cooling units located around the accelerator's ring. ITER's cooling units are located in one single installation.

Suppose that you're sitting on the bridge crane soon to be installed in the Assembly Hall — you are facing west and here's the panorama that you would be taking in. Down on the floor to the left, what appears to be crop circles in concrete is in fact the deep anchorage plots of the giant Sector Sub-Assembly tools presently under fabrication in Korea.   On both sides of the steel structure of the building, the railings that support the beam you're sitting on run the whole length of the Assembly Hall and will later run to the far end of the Tokamak Building.   Further out is the circular pit where the ITER Tokamak will be assembled. If you perch long enough on the crane beam, you'll see the thick concrete walls of the bioshield rise, level after level, until they form a circular fortress around the Tokamak.   Unfortunately, no one will ever sit on the  bridge crane ... It's a pity, for the view is really breathtaking.

At the PRIMA neutral beam test facility in Padua, Italy, the components of ITER's most powerful heating system—neutral beam injection—will be tested in advance of ITER operation.   Europe, Japan and India are contributing all components according to the specifications of Procurement Arrangements signed with the ITER Organization; Italy has built the facility as a voluntary contribution to the neutral beam development program.   Since late 2014, components have been arriving on site for installation at the SPIDER test bed, a 1:1-scale ion source that will be used to develop the technology for the production of negative ions. Deliveries have included a beam dump supplied by India, a high-voltage deck supplied by Europe, and power supply components from Japan.   On 1 March, a flag-off ceremony was held at ITER India premises in Gandhinagar, as the latest shipment of in-kind components procured by India left for PRIMA. Nine trucks containing components for SPIDER's 100 kV power supply—transformers, switching modules, controllers, high-voltage racks, cables disconnector switches—are now en route to the port of Mundra, on India's west coast, for shipment to Italy.

Two 750-tonne crane bridges, operating alone or in tandem, will be used to lift the heaviest components during the assembly phase of the ITER Tokamak.   Each crane will be assembled from two 47-metre support beams, or "girders," that span the width of the Assembly Hall. The girder pairs, in turn, will be equipped with two trolleys to allow for flexibility in the handling of the loads.   The first two girders left their manufacturing site in Aviles, Spain, on 25 and 26 February and are now en-route to Fos harbour where they are expected on 8 March. The other two are set to sail in the coming days.   Meanwhile at the REEL factory in Villefranche-sur-Saône, close to Lyon, France, four 375-tonne trolleys are undergoing their final acceptance tests. Five metres high, 10 metres long and 5 metres wide, they are among the largest and most powerful ever built in Europe for application in the nuclear industry. They will be delivered on site in April.

The European Domestic Agency has announced the completion of 20 kilometres of niobium-tin (Nb3Sn) superconductor for ITER's giant D-shaped toroidal field coils.   This represents a little over one-fifth of the total amount of conductor (88 km) required for the machine's 18 magnets plus one spare. Five other ITER Domestic Agencies are contributing toroidal field conductor as part of their in-kind contributions to the project: China, Japan, Korea, Russia and the United States.   The European milestone is the result of more than six years of intensive collaboration with industry. The first contracts for the building blocks of the conductors—superconducting strand—went to Luvata (copper strand), Oxford Instruments Superconducting Technology and Bruker European Advanced Superconductors (Nb3Sn strand). The next tasks of cabling, jacketing and spooling were undertaken by the ICAS consortium (ENEA, Tratos and Criotec), which successfully produced 30 toroidal field conductor lengths.   The conductor lengths were progressively delivered to ASG Superconductors SpA in La Spezia, Italy, where winding operations are currently underway.   ITER's toroidal field magnets will create a powerful magnetic cage to confine the hot plasma in the centre of the plasma chamber away from the walls of the vessel. Europe is responsible for producing 10 toroidal field coils and Japan, nine.   Read the full story on the European Domestic Agency website.

How to sustain and measure temperature in a fusion plasma? This challenging task requires different heating systems and diagnostic tools. Information on the spatial distribution of temperature is one of the key elements for improving and controlling plasma performance. In a recently published Nature Physics article, Didier Mazon, Christel Fenzi and Roland Sabot, of CEA's Research Institute on Magnetic Fusion (IRFM) explore the fascinating realm of ultra-hot temperatures. Illustration of a new X2D diagnostic: spectroscopy for ion temperature measurement in the WEST tokamak. Click here to read the whole article in Nature Physics.

At the CEA Saclay's Cold Test Facility, near Paris, JT-60SA's first toroidal field coil has completed its round of tests at cryogenic temperature (4.5 K). "The coil became superconductive and reached its full current (25.7kA) without any problem," said Pietro Barabaschi, Home Team Project Manager for Europe's contribution to the Broader Approach project. A ceremony will be organized at CEA Saclay on 6 April prior to shipping the coil to Japan. Read the story on the European Domestic Agency's website.