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A large gathering of fusion scientists such as the 24th IAEA Fusion Energy Conference held in San Diego on 8—13 October offers a unique vantage point to assess the progress of fusion research worldwide.
The 400 papers and posters that were presented throughout the week—some 70 being ITER-related—clearly demonstrated that, in many critical areas, researchers are reaching a much better understanding of the phenomena that control plasma behaviour—and we all know that this fundamental knowledge is essential to the success of our project and, beyond, to the future of fusion energy.
One of the highlights of the meeting was the presentation of JET's results: now equipped with an ITER-like wall, JET, together with ASDEX Upgrade, is answering critical questions on how tungsten would affect plasma performance in ITER. The results on fuel retention on JET are encouraging and we are awaiting further results from JET on how to optimize plasma performance.
The synergy between exploratory experiments on ASDEX Upgrade and follow-up experiments on JET has been valuable. This has implications for the role of satellite experiments in the Member states when ITER comes into operation.
The superconducting tokamak facilities, EAST, KSTAR and JT-60SA, clearly see how they could contribute to ITER. It was also pleasing to hear that the SST-1 Tokamak at IPR (India) has been reassembled and that commissioning of the superconducting magnets is underway.
We were all very interested in the new data on disruptions and runaway electrons that the teams working at JET, Alcator C-Mod, DIII-D and T-10, as well as other machines, have accumulated. Innovative techniques are being developed to minimize the impact of the runaway beams on the plasma-facing materials on DIII-D, which is good news for our community. The effectiveness of a second gas valve to reduce the asymmetry in the radiated power during a disruption was studied on C-Mod.
The disruption observations from JET indicate that there are significant differences between a carbon divertor and a tungsten divertor. The plasma current decays more slowly and the vertical position also evolves more slowly. This is probably related to the decreased radiated power—however, the duration of the halo currents is greater.
An intriguing result from analysis of NSTX disruptions is that 98 percent of disruptions can be flagged with at least 10 ms of warning with only 6 percent of false positives.
These results combined with other results on disruption mitigation give greater confidence that a sufficiently reliable disruption mitigation system can be developed for ITER, though further work is needed.
An increasing body of fundamental knowledge is also being accumulated in the field of ELM control, which will lead us to re-evaluate how to either mitigate the impact of, or preferably suppress, ELMs by means of the in-vessel coils. ASDEX Upgrade, DIII-D and MAST are strongly contributing to this exploration and understanding as well as theorists from around the world. In addition, interesting new data using other techniques, including pellet injection, to control ELMs were shown by DIII-D, EAST and KSTAR.
Increasingly detailed analysis of stability and confinement characteristics of H-mode plasmas are advancing in impressive fashion: the conference heard of the remarkable agreement between the predictions of the "EPED" code and measurements of limiting pedestal pressure in many tokamak experiments.
An interesting new analysis of the influence of isotopic mass on the confinement characteristics of H-mode plasmas was also reported from JT-60U, and striking results from nonlinear 3D modelling of individual ELMs with the JOREK code were also presented. An extensive review of recent data on the dependence of the H-mode power threshold carried out by the ITPA will also give us food for thought.
On the first day of the conference, ITER Director-General Osamu Motojima gave a status report on ITER in the first technical session of the meeting. Later that day, there was a session devoted to ITER physics, scenarios and heating and current drive technology. These two sessions provided an excellent introduction and overview about the status of the project and recent scientific and technical achievement.
David's presentation related ITER's plans to achieve burning plasma conditions to some of the recent work highlighted at the meeting. Based on successfully achieving burning plasma conditions; Rich's presentation described how ITER would be able to advance our understanding of deuterium-tritium burning plasmas far beyond what we achieved on JET and TFTR during the 1990s. The presentation described not only the progress that both JET and TFTR had made but also the outstanding scientific issues.
The results described above are not a comprehensive summary of the meeting but merely some casual observations of interesting results to stimulate people to read the conference proceedings and articles in Nuclear Fusion.
Better, maybe, than a dramatic announcement of a revolutionary breakthrough, the conference provided a clear and reassuring image of a community that is marshalling its facilities and intellectual resource to make fusion happen and in the process, addressing key issues of importance to ITER.
http://www.iter.org/newsline/242/1361-Rich Hawryluk, ITER Deputy Director-General and David Campbell, Head of the Directorate for Plasma Operation
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Although it may appear as a faraway activity, the assembly of the ITER Central Solenoid (the backbone of the machine's magnetic system) and its installation inside the Tokamak were discussed at two Preliminary Design Review meetings held in Cadarache last week.
The US Domestic Agency (US-DA) is responsible for the construction of the 6 central solenoid modules plus one spare, and for the associated pre-compression structure. Due to its large size, the central solenoid will not be delivered by the US-DA as a single piece and thus needs to be assembled on the ITER site in Saint-Paul-lez-Durance.
The US partner is in charge of the design, procurement and delivery of the special assembly tools that are necessary to assemble the six modules with the pre-compression structure and the current lead extensions. The assembly itself will be carried out by the ITER Organization. Once assembled, the 17-metre-high central solenoid will be lifted and transported to the Tokamak where it will be lowered into its 4.4-metre-diameter pit with a clearance of 42 mm.
Both reviews—assembly tooling and installation—were chaired by Michel Huguet, former director of the ITER Naka site during the Engineering Design Activities (EDA) phase of the project. Most of the presentations were delivered by Mike Cole and Robert Hussung, both staff members of the US-DA, leading the development for special tools.
The tools include: an assembly platform where the modules will be stacked; a lifting device to handle the modules and stack them on top of one another with millimetre accuracy; a rotating fixture to turn over the three lower modules; a man-lift to allow performance of operations inside the inner bore of the modules; a drill guide fixture to allow drilling holes in the interface between modules in order to insert shear pins preventing relative displacement between modules; a lead extension alignment fixture, and a lead support structure.
Delivery of these tools is planned to start in June 2016, matching the ITER Organizations's needs for the assembly of the machine's central magnet. Manufacturing of the early delivery items, the assembly platform, and the lifting tool is expected to start in early 2015.
Once installed in the Tokamak, the central solenoid will be supported at its bottom on lower supports attached to the bottom of the toroidal field coils and kept centred at its top by a system of rods attached to the top of the toroidal field coils. The lower supports are thus the first components to be put in place. The central solenoid can then be lifted by the crane and lowered into the Tokamak.
The review panel was pleased with the quality of the presentations which helped everyone to understand how the tooling is designed and the way it is planned to be used. The reports demonstrated the high involvement of the team and its capacity to address the challenge of accurately positioning heavy loads given the fact that the total weight of the assembled central solenoid is around 1,000 tons.
Nevertheless, several chits are in preparation by the review panel and will be communicated through the review report within a few weeks. This will help the design team to focus on the few remaining issues to be tackled before moving into the final design phase.
http://www.iter.org/newsline/242/1358-Paul Libeyre, Section Leader, ITER Central Solenoid & Correction Coils
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Ever since Dr. Heike Kamerlingh Onnes walked the pace of superconductivity back in 1911, there have always been scientists endeavouring to exploit its tremendous properties through powerful, high magnetic field magnets.
These endeavours are turning into a reality at ITER, as the largest and most powerful superconductive magnets ever designed, with an individual stored energy of 2.2 Gigajoules (GJ), are being manufactured.
The toroidal field coils are the ITER magnets responsible for confining the plasma inside the vacuum vessel, using cable-in-conduit, niobium-tin-based conductor technology.
Procurement for the 19 toroidal field coils is shared between the Japanese and the European Domestic Agencies.
Following the last call for tender in August 2012, the first of a series of procurement contracts of the nine Japanese toroidal field coils has been awarded to Mitsubishi Heavy Industry as a main contractor, with Mitsubishi Electric Corporation (MELCO), as a sub-contractor (a well-known stakeholder in superconducting magnet world).
| | Toroidal Field Coil Main Parameters
Number of coils 18
Number of turns per coil or WP 134
Stored magnetic energy, for the 18 TFCs 41GJ
Operating current 68 kA
Nominal peak field 11.8 T
Coil total length 1,7150 m
Coil total weight 298.5 t
Winding Pack weight 110.5 t
Coil Case weight 188 t
Centring force per coil 403 MN
Vertical force per half coil 205 MN
WP Conductor length 4,570 m | | |
Toroidal field coils are encased in large stainless steel structures. Procurement of the nineteen encasing stainless steel coil structures (TFCS) is the responsibility of the Japanese Domestic Agency, who recently placed two contracts respectively for first-of-series European TFCS with Hyundai Heavy Industry in Korea and for Japanese TFCS with Mitsubishi Heavy Industry in Japan.
With a total weight of 3,400 tons, the "superstructure" of toroidal field coils is pushing the limits of manufacturability. Millimetric tolerances require state-of-the-art welding techniques (plate thickness on 316LN is up to 180 mm) to reach high quality requirements. As a result it is necessary to use specialists in heavy industry.
From 1-3 October 2012, the Collaboration Toroidal Field Coil Working Group met in Naka, Japan after visiting Hyundai Heavy Industry, Mitsubishi Heavy Industry and MELCO manufacturing. This meeting was attended by toroidal field coil and TFCS technical responsible officers from the ITER Organization, the European Domestic Agency and the Japanese Domestic Agency (JA-DA). Several specialists from JA-DA supplier Mitsubishi Heavy Industry were also invited to participate in the meeting.
Such meetings are essential for resolving common toroidal field coil system issues between both Domestic Agencies and their multiple suppliers, and to manage the interfaces and tolerances between the winding packs and the coil structures.
It goes without saying that regular contact with the Domestic Agencies' industry, through meetings with technical responsible officers will guarantee the prompt solving of any issues that may arise within such a challenging production environment.
The manufacturing of the first series of double pancakes as part of first winding packs by both Domestic Agencies is planned to start in September 2013, with delivery of the first winding pack in 2014 bringing up to full speed the.series production.
Given that the knowledge-based coil fabrication will be very dynamic, improving insight in those magnets tolerances will be essential, as discussed with technical responsible officers Norikiyo Koizumi (JA-DA) and Alessandro Bonito Oliva (EU-DA).
Bonito Oliva reported additionally on recent progress concerning the commissioning of the European toroidal field winding tooling facility, the heat treatment oven and ongoing qualification tasks on joint, helium inlet and impregnation trials.
In spite of the difficulties of coordinating fabrication work with such a vast logistic and high production rate, the ITER Organization is confident in the ability of the Domestic Agency suppliers and of the ITER-Organization-Domestic Agency team's capacity to continue working in a cooperative and synergetic manner in order to reach our common goal.
The Collaboration Meeting is also an opportunity to showcase the work done in the Japanese and European Domestic Agencies. The substantial progress achieved by both would not have been possible without an effective collaboration within the toroidal field team.
http://www.iter.org/newsline/242/1351-Arnaud Foussat, Section Leader, ITER TF Coil Section
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For almost one century—it was founded in 1913—the French monthly Science et Vie (circ. 290,000) has brought the marvels of science and technology to an ever-expanding public.
In 1988, Science et Vie Junior, aimed at the 11 to 17 age group, was created as an offspring of the main magazine. The editors had realized that reaching teenagers required a different approach, both in the layout and in the language used.
Science et Vie Junior, however, explores the same world as its more senior Science et Vie. This month for instance, the magazine publishes a special issue on "the different states of matter," promising its young audience they will remain scotchés ("mesmerized") by what they will discover.
The ITER project was cited as a mesmerizing example of the use of plasma. Six full pages are devoted to the physicists, Richard Pitts among them, who "want to light a star" in Cadarache and extract "as much energy from one litre of water as one gets from burning 1,000 litres of oil."
The article is remarkably clear and explanatory—an ideal entry point for anybody, aged 11-17 or not, wishing to understand what the ITER project is all about.
Science et Vie Junior, Hors série n°96, octobre 2012, € 5.50
http://www.iter.org/newsline/242/1357
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When travelling, always take books with you. When they visited ITER early this week, Li Gui Hua, deputy director-general of the Executive Office at MOST (the Chinese Ministry of Science and Technology) and Mingqin Ding, deputy director-general of the Chinese Domestic Agency ITER China followed this wise recommendation. They came with some 80 kilos of Chinese textbooks, which they offered to the PACA International School library. The delegation they headed included two journalists from China's Science and Technology Daily, and communication officers from ITER China. Before visiting the worksite and meeting the ITER senior management, the group met with the communication team at ITER and exchanged views on their respective practices. However different the context, "communicators" here and there pursue the same objective: explaining what is at stake with ITER and winning public support for the project.
New Japanese Consul General visits ITER
Masaaki Sato, the recently appointed Consul General of Japan in Marseille, visited ITER on Friday 19 October. Mr Sato, who speaks flawless French, is a veteran diplomat with a long experience in international cooperation. He joined Japan's Foreign Ministry in 1977 after completing a law degree at Tokyo Keio University.
Mr Sato's previous postings include Canada (Montreal) and the Democratic Republic of Congo. As Consul General of Japan in Marseille, his jurisdiction extends over four French administrative regions: PACA, Languedoc-Roussillon, Midi-Pyrénées and Corsica. Some 2,400 Japanese nationals live in this area, half of them married to French citizens.
http://www.iter.org/newsline/242/1359
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The third forum for the eight Korean Domestic Agency (KO-DA) industries that participate in supplying the ITER procurement items took place on 16 October at ITER Korea with officials from the Ministry of Education and Technology, senior managers from the KO-DA, and Dr. Mitsunori Kondoh from the ITER Organization.
During the meeting, valuable discussions took place about the lessons learned in seeking ways to enhance Korean industries' contributions to the overall ITER project.
Both the Korean government and the KO-DA were delighted with the KO-DA suppliers' consensus that they would do their utmost to meet the schedule and quality requirements, thus enabling Korea to comply with its obligations to provide ITER with its in-kind procurements.
http://www.iter.org/newsline/242/1362-Ji-Min Song, ITER Korea
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The Council Room is one of the most striking features of the ITER Headquarters building. Located on the fifth floor of the building and opening onto a terrace to the northwest, it is the only room in the building to offer both a platform and a countryside view.
Using a template of the large oval table that will be the room's centrepiece, workers were busy last week installing video and communication networks.
The Eleventh ITER Council is scheduled in less than six weeks ...
http://www.iter.org/newsline/242/1360
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