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Latest ITER Newsline

  • Summer postcards from the ITER worksite

    The latest harvest of ITER construction photos may be taken from the same point—the tallest crane on site—but there is always an abundance of new detail to be g [...]

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  • The ring fortress

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  • The wave factory

    A year ago, work was just beginning on the steel reinforcement for the building's foundation slab. The Radio Frequency Heating Building is now nearing the last [...]

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  • It's all happening inside

    Since the giant poster was added to the Assembly Hall's completed exterior in June 2016 the building has lookedfrom afar like a finished project. Butinside, tea [...]

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  • Along skid row

    They look like perfectly aligned emergency housing units. But of course they're not: the 18 concrete structures in the ITER cryoplant are massive pads that will [...]

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Of Interest

See archived articles

Designing an antenna the size of a bus

-Sabina Griffith

One of the two impressive ICRF antenna systems that will deliver 10 MW of heating power each into the ITER machine. (Click to view larger version...)
One of the two impressive ICRF antenna systems that will deliver 10 MW of heating power each into the ITER machine.
The ion cyclotron resonance heating (ICRH) system, one out of three heating systems installed in ITER, will deliver 20 MW of radio frequency power to the plasma for up to one hour. The power will be injected at radio frequencies through what we call "antennas," however, ITER antennas have very little in common with the one attached to the standard radio in our kitchen. These components will measure 1.8 x 3.5 x 2.5 metres and weigh 45 tons (dry weight). And—who would have guessed—there is some very sophisticated technology hidden inside the beast.

It is Europe's responsibility to deliver two of these high-tech components to ITER. In 2010, the ITER Organization signed a Task Agreement with the European Domestic Agency which, in turn, signed a contract for the "build-to-print" design of these impressive antennas with the CYCLE consortium, made up of several European fusion associations with ICRH expertise: CCFE, UK;  CEA, France; ERM, Belgium; IPP, Germany; and ENEA-Torino, Italy.

More than 50 experts on ion cyclotron radio frequency design, engineering, and physics met in Cadarache last week for the antennas' preliminary design review, conducted by Jean Jacquinot. (Click to view larger version...)
More than 50 experts on ion cyclotron radio frequency design, engineering, and physics met in Cadarache last week for the antennas' preliminary design review, conducted by Jean Jacquinot.
On 22-24 May, more than 50 people—including experts on ion cyclotron radio frequency design, engineering, and physics; representatives from the European, Indian, and US Domestic Agencies; technical representatives from interfacing ITER systems; and, of course, members of the CYCLE design team—met in Cadarache to review the preliminary design. The review panel was chaired by Jean Jacquinot, former director of JET and one of the pioneers of the ICRH technology.

The design of ITER's ICRH antennas will be the quintessence of technologies developed for machines like Alcator C-mod, JET, Asdex-Upgrade, TEXTOR and Tore Supra. "The challenge in designing such an apparatus for ITER is not only the power increase to 10 MW for each antenna and the associated large electric fields," explains Jacquinot, "but the fact that this is a plasma-facing component that has to withstand neutron bombardment and high heat fluxes from the plasma. In addition, these components will require permanent water cooling and they will have to squeeze into an equatorial port plug, allowing only very tight tolerances."

"We try to make use of available technology as much as we can," ITER's Ion Cyclotron Section Leader Bertrand Beaumont comments. "But of course some new developments are necessary, such as the Faraday screen—a sandwich-like structure made of beryllium, hardened copper alloy, and stainless steel that covers the front face of the antenna."

"One of the open questions that call for further study is the behaviour of the ceramic vacuum windows in a nuclear environment," adds Philippe Lamalle, technical responsible officer for the antennas.
 
 "The design review was an excellent and in-depth review of the antenna system, showing us that we are on the right track," said Dharmendra Rathi, technical officer for the system, at the end of the meeting. With no showstoppers identified, the ICRH team will now prepare for the next mileston: the final design review scheduled for 2015.


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