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When fusion was almost there

Fifty years ago, in 1964, human beings believed in progress. Manned space capsules were routinely sent into space, a revolutionary supersonic commercial airliner was nearing the prototype stage, the computer mouse had just been invented, and the official decision had been taken to build a cross-Channel tunnel. Nothing epitomized this optimistic and conquering mood more than the 1964 New York World's Fair. Dedicated to 'Man's Achievement on a Shrinking Globe in an Expanding Universe," the huge exhibition showcased and exalted the promises of mid-twentieth century technologies. Fusion energy was present, staged and dramatized in the spectacular Progressland pavilion by General Electric and the Walt Disney Studios. General Electric had entered fusion research as early as 1956, at a time when physicists such as Amasa S. Bishop, director of the US program in controlled fusion (Project Sherwood), were convinced that 'with ingenuity, hard work, and a sprinkling of good luck, it even seems reasonable to hope that a full-scale, power-producing thermonuclear device may be built within the next decade or two.' In April 1964, the 'next decade' had arrived and, with the help of Disney's design experts, General Electric produced the Nuclear Fusion Demonstration, one of the Fair's most exciting attractions. Here's how it was described in the New York World's Fair Official Guide: 'In the first demonstration of controlled thermonuclear fusion to be witnessed by a large general audience, a magnetic field squeezes a plasma of deuterium gas for a few millionths of a second at a temperature of 20 million degrees Fahrenheit. There is a vivid flash and a loud report as atoms collide, creating free energy (evidenced on instruments).' The 'fusion bangs,' which occurred every 4-6 minutes, were loud enough to leave a lasting impression on the visitors. 'After a countdown, brilliant flashes of light and a loud popping crack would signify that GE was successful in tapping into the nuclear science of sun building,' writes a Disney historian. 'Clerical workers who staffed the pavilion soon grew accustomed to the loud explosions emanating from the dome.' Many years after Progressland had closed and moved to Disneyland, they still had a vivid memory of the experience. Where did these 'loud popping cracks' come from? Certainly not from the 'collision of atoms' in the fusion installation (a theta-pinch fusion device) that stood on a plinth at the centre of a large amphitheatre. More probably, they emanated from the discharging of the capacitor bank that fed power to the device. The Fusion Demonstration left many visitors convinced that fusion-generated electricity was at hand, which of course did not reflect the actual state of fusion research. As General Electric reviewed its corporate involvement in fusion one year later, it concluded that 'the likelihood of an economically successful fusion electricity station being developed in the foreseeable future is small.' In order to hasten the 'foreseeable future,' fusion physicists needed to delve more deeply into the complexities of plasma behaviour. And they did: contrary to General Electric's pessimistic conclusion, the decade that followed the 1964 World's Fair was one of spectacular progress not only in fundamental physics but also in fusion technology. With the advent of the tokamak—a Russian concept soon adopted by the worldwide fusion community—and an understanding of the scaling laws that rule energy confinement, researchers were able to dramatically improve performance. The 'foreseeable future' was back; in 2014, it is closer than ever.

Rendez-vous in Seoul

The first Asian ITER Business Forum (IBF Korea/14) will take place in Seoul, Korea, from 1 to 4 July 2014. This event aims to develop industrial partnerships and business relations between industries involved in the ITER Project, in fusion, and beyond. It is organized by the Korean Domestic Agency for ITER with the participation and support of the ITER Organization, the European Domestic Agency Fusion for Energy (F4E) and the other Domestic Agencies. IBF Korea/14 will provide industries with updated information on ITER status, procurement procedures and forthcoming calls for tender (2014-2015). There will be special focus placed on the procurement status of the ITER Domestic Agencies and on their main suppliers (manufacturing status and potential needs in terms of partnerships, subcontractors, local support). This event will include an industrial conference, one-to-one meetings (pre-reserved on line) and an optional program of technical tours. We hope you will take this opportunity to make business contacts with European or Asian companies involved to the ITER Project and your core business. We look forward to seeing you at IBF Korea/14 in Seoul.

Spider webs of steel

Imagine a spider web made of steel threads that are 40 millimetres in diameter. Now imagine a structure that is built from 16 of these spider webs superimposed and you will have an idea of the complexity of the rebar at the centre of the Tokamak Complex Seismic Pit. Spiders spin their web out of instinct. Rebar workers follow detailed execution drawings that result from a long chain of calculations that includes load and stress definition, safety requirements, code crunching and, eventually, the engineers' interpretation. The process begins quite naturally with the definition of the buildings that the structural elements will support. How big are they? How much do they weigh? And what safety functions—such as protection against radiation, confinement, seismic isolation—must they fulfil? But above and beyond the weight of the building itself, equipment loads must be taken into consideration—for example the 23,000 metric tons of the machine or the giant neutral beams injectors—as well as forces resulting from cryostat thermal shrinkage, possible seismic events, and normal or accidental vertical displacement of the Tokamak during operation. 'Safety provisions are also part of the calculations,' stresses Laurent Patisson, who heads the Nuclear Buildings Section. 'In some areas such as in the Tokamak support zone, safety provisions of 150 percent for what we call category IV events, such as the reference earthquake, have to be considered.' In an average building, loads are measured in decanewtons. In the Tokamak Complex, meganewtons are used. These units describe the force required to give an acceleration of one metre per second to a mass of one thousand tonnes ... every second. Computing this impressive and voluminous data into models gives rebar design specialists the quantity of steel necessary to guarantee the robustness and safety of each edifice. 'The code tells us how much steel by linear metre of concrete is required, but it doesn't say much about how the rebar should be arranged,' explains Laurent. 'This is for the structural analysis engineer from Engage to determine.' (Engage is the European consortium that was awarded the Architect Engineer contract for the construction of the Tokamak Building.) More than 4,000 metric tons of rebar will go into the Tokamak Complex foundations, the B2 slab, with steel density at its highest in the central, circular area that will support the ITER machine (one fourth of the total rebar). The design work on this section was particularly demanding—the rebar arrangement must meet the required steel density while preserving the constructability of the slab. In simple terms: however dense the rebar, some access has to be preserved for the nozzle of the concrete pumps and the concrete vibrating tools. The Rebar Minutes Drawings produced by the structural analysis engineer have now been refined by a draftsman and communicated to the contractor in charge of the actual laying of the rebar. Based on the detailed Construction Design Reinforcement Drawing, the contractor will implement its own methodology and techniques, validated by Engage. 'The European Domestic Agency, the ITER Organization and a specialized contractor implement all the necessary controls,' adds Laurent. 'Site surveillance reports are produced twice a week by ITER's Building and Site Infrastructure Directorate and soon, it will be done daily.' Rebar workers are now proceeding. However for the most complex area of the rebar arrangement, where orthoradial and orthogonal arrangements meet, a last trial is being implemented on the 150 m², 1:1-scale B2 slab mockup located to the west of the Seismic Pit. 'We need hands-on experience of the difficulties inherent to this type of interfacing,' says Laurent. Spiders definitely have it easier...

Three days for diagnostics

The fourth annual All Diagnostic Domestic Agency meeting took place at ITER Headquarters in mid-March, attended by diagnostic heads from the Domestic Agencies and members of the ITER Diagnostic Division. During the three-day meeting, attended by approximately 20 people, sessions were held to highlight progress made on diagnostic systems since last year, address issues related to the coordination of design development and system integration (in particular in the ports), and to encourage communication between the Domestic Agency teams and the ITER Organization. Characterized by lively debate and sometimes disagreement, participants felt that the three days had been 'invaluable' and that the informal style permitted the generation of new ideas. Each session was chaired by representatives from a different Domestic Agency along with a co-chair from the ITER Diagnostics Division; this organization, launched last year, has proven very successful. Papers presented at each session were followed by Q&A sessions. The wide range of topics covered served to keep all aware and facilitated better understanding of important diagnostics issues such as the freezing of interfaces to synchronize diagnostic development schedules. A number of key actions—often addressed by joint ITER Organization-Domestic Agency work teams during the meeting—were agreed and plans were made to ensure implementation, with good firm outcomes. Paul Thomas, director of the ITER CODAC, Heating & Current Drive Directorate, opened the meeting with encouragement for all and pointed out key diagnostic issues for 2014. He also commented about the good team spirit and encouraged everyone to keep up the good work. Michael Walsh, Diagnostics Division Head, complimented all for the significant progress made in the last year. Once again, this face-to-face meeting helped engender and foster excellent team spirit and reinforce the links within all diagnostics teams.

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Calming Plasma's Stormy Seas

​For decades, controlled nuclear fusion has held the promise of a safe, clean, sustainable energy source that could help wean the world from fossil fuels. But the challenges of harnessing the power of the sun in an Earth-based nuclear fusion reactor have been many, with much of the progress over the last several years coming in incremental advances. One of the key technical issues that has puzzled physicists is actually a common occurrence in fusion reactions: plasma turbulence. Turbulence inside a reactor can increase the rate of plasma heat loss, significantly impacting the resulting energy output. So researchers have been working to pinpoint both what causes this turbulence and how to control or even eliminate it. Now simulations run at the National Energy Research Scientific Computing Center (NERSC) have shed light on a central piece of the puzzle: the relationship between fast ion particles in the plasma and plasma microturbulence. Read the whole article on NERSC website.

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