Whether working to design and test prototypes, develop advanced control systems, resolve open physics questions, or manufacture technically challenging components and systems, individuals and teams working within the framework of ITER-related contracts are bringing creative and innovative solutions into play.

New research from the Princeton Plasma Physics Laboratory (PPPL) predicts that the maximum high heat flux from the ITER Tokamak can be handled by the ITER divertor—the component at the bottom of the machine that, in extracting heat and ash produced by the fusion reaction, withstands the highest surface heat loads of the machine. Breaking with projections extrapolated from existing tokamaks that had suggested that the heat flux could be so narrow and concentrated as to damage the front-facing plates of the divertor and require frequent repair, an international team led by PPPL physicist C.S. Chang has painted a more positive picture. Chang's team used the highly sophisticated XGC1 plasma turbulence computer simulation code developed at PPPL to create the new estimate. The simulation projected a width of 6 millimetres for the heat flux in ITER when measured in a standardized way among tokamaks, far greater than the less-than 1 millimetre width projected through use of experimental data. Physicist C.S. Chang, from the Princeton Plasma Physics Laboratory. The discrepancy between the experimental projections and simulation predictions stems from the fact that conditions inside ITER will be too different from those in existing tokamaks for the empirical predictions to be valid, according to Chang. Key differences include the behaviour of plasma particles within today's machines compared with the expected behaviour of particles in ITER. For example, while ions contribute significantly to the heat width in major worldwide facilities, turbulent electrons will play a greater role in ITER, rendering extrapolations unreliable. Chang's team used basic physics principles, rather than empirical projections based on the data from existing machines, to derive the simulated wider prediction. The team first tested whether the code could predict the heat flux width produced in experiments on US tokamaks, and found the predictions to be valid. Continue to the PPPL website for the complete article.

The four converter-transformers that passed the ITER gate at 3:00 a.m. last Wednesday are part of a set of 16 to be installed outside the twin Magnet Power Converter Buildings. (Fourteen are needed for First Plasma, an extra two for subsequent operations.) Procured by China, each of the 128-tonne converter-transformers will be paired to a rectifier and connected to the machine's ring-shaped poloidal field coils. The transformers will bring down the 66 kV AC industrial current to approximately 1 kV; the rectifiers will convert it into DC current, just like a cell phone or laptop adapter transforms the 110 or 220 volts from the wall plug into 9, 12, or 24 volts of DC current.   The difference, as in everything ITER, is in size and power. "With the exception of aluminium smelters, I can think of no industry that requires DC current higher than ITER," says Ivone Benfatto, head of the ITER Electrical Engineering Division.   However contrary to aluminium smelters, the ITER magnets need to be fed current in two directions in order to control the magnetic fields and optimize the duration of the plasmas. "In designing these very challenging components, we have also drawn from the experience in motor speed drive, like the electrical motors that power high-speed trains, whose current needs to be inverted when the train changes direction or when regenerative braking is activated."   And whereas trains can accept interruptions in current transmission, the ITER magnets can't. High voltage direct current (HVDC) power transmission lines and their bypass systems also provided a third input of industrial knowhow to the design of the ITER converter-transformers.   "Sometimes," muses Ivone, "we tend to forget that some of the components that are delivered to us are technological marvels ..."

This week, three diverse groups of people—core developers of the EPICS toolkit, of the Control System Studio visualization software, and of the areaDetector 2D image processing framework—are meeting at ITER Headquarters for three days of discussion and lively debate. EPICS is the software backbone of the CODAC control system. It comprises a set of tools, network protocols and hardware drivers centred around a highly flexible distributed database of process variables. This will provide the glue to adapt, fit and hold together ITER's nearly 200 plant systems, forming a single integrated control system running the ITER Tokamak.   Control System Studio (CS-Studio) will power ITER's dashboard, what we call the visualization layer—panels, graphs, sliders, symbols, metres and switches on the operator consoles in the ITER control room. It also runs important central services for alarm management and logging, as well as the non-scientific archiving and the electronic logbook.   areaDetector is a modular Lego-style system of software "bricks" to build EPICS controlled image acquisition and processing systems. It integrates cameras and other two-dimensional detectors—from still image cameras to megapixel detectors—delivering more than 100 images per second, adding a flexible set of filtering, streaming and analysis functions.   All three efforts are free and open-source software projects, developed collaboratively over many years by control system engineers from laboratories and institutes around the world. And as in all collaborations, even the newest communication technology won't cover everything; some issues and ideas can only be efficiently discussed and resolved sitting around a table. And so, the core developers groups meet twice a year, hosted by one of their institutes, to argue about and review proposed changes, discuss and plan their releases, develop ideas and toss them apart.   Similar to the projects that communicate and overlap, the developers meet separately—but in parallel and at one site—to allow for ad-hoc shared sessions on interfaces and other topics they share interest in. This week, ITER hosts 16 external visitors from Germany, Great Britain, Sweden, Switzerland and the United States; each group will be joined by a few more remote developers.   The CS-Studio group will dedicate some of their time to a code-a-thon, a sprint coding session to deal with existing issues and work on short-term objectives in an agile style, with instant peer reviews. "For ITER, the focus will be on the functions required for the temporary control rooms, such as the logging of operator actions, support for multiple-screen operator terminals and the extension of the logbook to accept entries in different formats," says Nadine Utzel, who will represent the CODAC team in the CS-Studio meeting.   The big EPICS topic this time: the existing software release, version 3, is about to be merged with a set of newer developments including a new network protocol, dubbed version 4, to form the next major version, EPICS 7. This requires lots of coordination between the groups to ensure that things continue to play well together. Time is already running short for the intended release later this fall, just in time to be included in the next CODAC Core System release 6.0.   "These meetings are very intense and efficient," explains Ralph Lange, an EPICS developer and CODAC team member, who organizes this week's meetings. "Giving a team a few days of complete immersion and focus with little disturbance from the home institute always creates a big push forward." A push that he hopes will help EPICS 7 to get ready in time.  

With its 54 large openings (or ports) the ITER vacuum vessel is a challenge to seal completely, and yet ultra-high vacuum is needed for the success of the plasma pulses. Vacuum Section Leader Robert Pearce describes the Herculean task: "The largest ports of the vacuum vessel have surface areas of 5 m². But an unsealed area the width of a human hair is enough to destroy the vacuum and halt fusion performance."   To leave nothing to chance a full-size replica of the largest equatorial ports has been designed and manufactured to test the vacuum sealing of what will be the largest port ever built on a tokamak.   The large seal test rig—4.8m (L) x 3.3m (W) x 4.8m (H)—is ready for factory acceptance testing at Vacuum Techniques in Bangalore, India. This full-size test rig has just been completed by Vacuum Techniques based in Bangalore, India. Vacuum Techniques, founded in 1989, is one of India's largest suppliers of vacuum equipment and a specialist in the design and manufacture of custom built equipment. "Their team of highly qualified engineers, led by Director Rangaroa, has been dynamic and resourceful in completing this key component," says Eamonn Quinn, Vacuum Mechanical Engineer.    The test rig is of an impressive size (nearly 5 metres in height and as many in length) and it weighs around 19 tonnes. It gives a preview of how the ITER machine will look when seen through the equatorial ports cells, as they are starting now to take shape on the construction site. It is due to be shipped to ITER shortly, where it will be used to test the assembly and function of a suite of large vacuum seals in order to validate the sealing technologies proposed for First Plasma and the subsequent operational phases of ITER.   "The seal test rig not only allows the largest demountable rectangular seals to be tested, but also enables us to prepare installation techniques which will be critical to achieving the required vacuum quality," states Pearce. "The rig can be heated to 240 ⁰C to simulate the baking of the ITER vacuum vessel and it also has the capability to apply loadings to the flanges to confirm the soundness of the sealing."

A new roll-on/roll-off ramp will facilitate the transhipment of components in Fos harbour.   Since early 2015, the seven ITER Members have been shipping components to ITER. The largest of these—called highly exceptional loads—can weigh up to 600 tonnes and require sophisticated logistics and robust infrastructures to transport and manoeuvre. When they reach the industrial harbour at Fos-sur-Mer (Marseille, southern France) the journey is far from over. A sequence of delicate operations still needs to be performed before the components can be transported over three to five nights to the ITER site, which is situated some 100 kilometres to the northeast.   This phase, which is essentially a transfer from sea-going vessel to land transporter, is by far the most challenging, as the more handling a component is subjected to the longer the time spent and the higher the cost and risk.   In order to simplify, secure and focus the transhipment sequences, new equipment has recently been added to the existing harbour infrastructure in Fos-sur-Mer.   A milestone in France's committment to ITER The new RO-RO ramp is a EUR 2.7 million investment jointly financed by Agence Iter-France, the agency that acts as interface between ITER and its host country (85 percent of the total cost); the cargo handling company Sosersid; the barge operator CFT; and ITER global logistics provider DAHER. "This equipment is an important milestone in France's commitment to the ITER Project," said Jacques Veyron, the director of Agence Iter France. The roll-on/roll-off ("RO-RO") ramp that was inaugurated on 20 September eliminates the need for vertical handling once the component has been unloaded from the ship. Although the ramp will be accessible for other uses, priority is given to the ITER loads when they come in.   Approximately 18 metres long and 30 metres large, the new RO-RO ramp is the largest of its kind in France. Representing an investment of EUR 2.7 million, it can accommodate combined loads (components and trailers) of up to 880 tonnes.   Four rectifier-transformers shipped by ITER China, each weighing close to 130 tonnes, were the first to use the ramp on their way to ITER last week (read related article).   In the six years to come, the ramp will accommodate approximately 200 highly exceptional loads (HELs)—among them the first toroidal field coil and the first vacuum vessel sector, both expected at the end of 2018.  

A third batch of electrotechnical equipment has left the port of Saint Petersburg, Russia, for delivery to ITER. On board are 85 tonnes of aluminium DC busbars and system components, part of an overall procurement package that includes some 5 kilometres of busbars (500 tonnes) as well as fast discharge units and switching networks. Busbars are the long metal components that will "snake" through the installation to feed the superconducting magnets with large amounts of current. The biggest are designed to carry close to 70 kiloamps of current to the 18 toroidal field coils of the machine; others will connect to the poloidal field coils, correction coils and the central solenoid. The first two batches of equipment were delivered and 2015 and 2016, and more are expected. The main supplier of this equipment is the Efremov Institute (NIIEFA), St. Petersburg. --Alex Petrov, ITER Russia