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ITER NEWSLINE 175
Developing materials resistant enough to withstand the high-power impact of the neutrons from deuterium-tritium (DT) reactions is of utmost importance for the future of fusion. This task has been assigned to the International Fusion Materials Irradiation Facility (IFMIF) which is presently in the Engineering Validation and Engineering Design Activities (EVEDA) phase.
The project is part of the Broader Approach that Japan and the European Union formally launched in 2007. IFMIF is coordinated from Rokkasho, in northern Japan, and headed by Pascal Garin, formerly of CEA's Institute for Magnetic Fusion Research (IRFM) and Agence Iter France.
In the future IFMIF plant, whose location has not yet been decided, two coupled accelerators will each deliver a deuteron (deuterium ion) beam of 125 mA at 40 MeV in continuous wave to a lithium loop. The interaction of the accelerated deuterons with the liquid lithium in the loop will generate neutrons similar to those produced in the DT fusion reactions. These neutrons will in turn irradiate reduced-scale samples of material to be tested, and other experiments in specific modules.
Construction of the EVEDA Lithium Test Loop (ELiTe) was completed in December 2010 at the JAEA Oarai Centre, Ibaraki prefecture. The installation was mildly affected by the 11 March 2011 earthquake—"Nothing really serious," says Garin—and its piping systems will require some checking before operations can resume.
Ten thousand kilometres from Rokkasho, at CEA Saclay in the Paris region, work on the scale 1:1 prototype accelerator, now officially named LIPAc (Linear IFMIF Prototype Accelerator), reached an important milestone last week.
The defining moment occurred in the evening of 4 May 2011, when the installation's injector produced its first proton (hydrogen) beam.
CEA's Raphaël Gobin, in charge of the injector design, manufacture and experiments, announced that—after the successful generation of a first plasma in the ion source a few days before—the first beam was measured in the specific blockhouse built for this occasion. This first beam was in pulsed regime whereas the final one will be continuous.
If LIPAc was a rocket, this would amount to the successful testing of the first stage ignite—a crucial step, but still a long way from commissioning the whole accelerator.
The accelerator (see graph) is made of a succession of systems and devices that accelerate and focus the deuteron beam, and eventually "dump" and absorb its 1.1 MW energy.
During the EVEDA phase, only the low energy section, which is the most challenging one, will be tested: the beam energy will reach 9 MeV at the end of the first cryomodule, while in IFMIF three extra cryomodules will bring the energy to 40 MeV that is required to optimize the production of neutrons.
"LIPAc is the accelerator of all records," explains Pascal Garin. "In terms of intensity, we're above the present state-of-the-art by a factor 100 and the energy of the prototype will be among the highest in the world, even higher than SNS in Oak Ridge."
Along with Japan, which is in charge of the infrastructure (buildings and power supply, cooling, central control command, etc.) several European institutes, coordinated by the European Domestic Agency Fusion for Energy, are contributing to LIPAc: the French CEA, the Spanish CIEMAT, the Italian INFN, the Belgian SCK•CEN.
Once tested in Saclay, the injector will be shipped to Rokkasho within one year. The other systems will then be installed and the whole LIPAc assembled by mid-2015. Two years of experiments are planned in order to reach a stable and continuous beam at the full energy. This will be accomplished around the end of the Broader Approach, in mid-2017.
In the actual IFMIF installation, the 40 MeV deuterium ions will generate an accumulated neutron flux (the "fluence") a hundred times that of ITER, and slightly above that of the future DEMO. The target samples will hence "age" some 20 to 40 percent faster than in an actual steady-state fusion reactor—a unique case of a particle accelerator that also accelerates time.
On Tuesday lunchtime, the windows rattled, the office buildings trembled and coffee sloshed around in cups. We had been warned, however: blasting operations have recommenced on the ITER platform for a period of approximately two weeks to complete the excavation for the Hot Cell Facility.
The Hot Cell Facility will be contiguous to the Tokamak Complex. Its foundations—less profound than those of its immediate neighbour—nonetheless require final blasting to finish the contours before foundation work begins.
The contractor responsible for excavation and foundation works, GTM Construction, is erecting a tower crane at each of the four corners of the Tokamak Complex area prior to concrete pouring works which are scheduled to begin in May and last the rest of the year.
At the peak of construction activity on the platform some 20 of these tower cranes will be in action, spread over the different work sites. The four silos of the on-site concrete batching plant are ready for the continuous ballet of trucks that will soon be seen loading, delivering, returning to wait in line, loading, delivering...
The workers involved with this heavy construction activity will of course need access to "comfort" facilities including locker rooms and a space for lunch. The European Domestic Agency is currently installing a staircase leading directly down from the platform to the comfort zone, some 60 steps below. From 70 today, the number of workers will rise steeply within the next months.
On the far side of the platform, the Poloidal Field Coils Winding Facility has taken on some of the colours of the ITER Member flags...but not for long. The red, green, blue and yellow metal sheets that can be seen on the south side of the building and that form part of the exterior cladding will soon be covered by sheets of another colour.
Five layers in all have been planned to isolate the poloidal field coil work space—where cleanliness is a priority—from the dust of the platform: an inner layer of sheeting containing small holes to absorb work area noise; insulation; and finally three layers of metal sheets sealed with tape for dust proofing.
Once completed, the Poloidal Field Coils Winding Facility will be champagne and orange coloured.
The University of Provence and the ITER Organization are glad to announce the 5th ITER International Summer School which will be held in Aix-en-Provence, France from 20-24 June, 2011. This school aims at preparing young researchers to tackle the challenges of magnetic fusion devices, and spreading the global knowledge required for a timely and competent exploitation of the ITER physics potential.
This year, the summer school will cover the interaction of magnetohydrodynamic instabilities with energetic particles, which is one of the key issues for the ITER reactor and burning plasmas in general. Lectures and specialized seminars will cover current developments in theory and experiments, but are also intended to give the basics of the field. Poster sessions allowing participants to show their work are planned.
* Topic : MHD and Energetic Particles
* Date : 20-24 June, 2011
* Location : Aix-en-Provence, France.
* Website : http://sites.univ-provence.fr/iterschool/index.html
* Contact : firstname.lastname@example.org
Thirty kilometres north of Cadarache, the Benedictine monastery of Ganagobie stands on a perfectly flat plateau overlooking the Durance Valley. The place has often been described as "an island in the sky," and an island it is ... lost in the soft waves of the hills and the mist rising from the river.
On a clear day, the view extends to the distant peaks of the southern Alps as far as Mount Viso on the Italian border. In all directions the panorama is spectacular. A thousand years ago, the place attracted monks seeking beauty and solitude. Sometime around the year 950, a church and a monastery were built and a Benedictine community established.
Monks lived, worked and prayed here throughout the Middle Ages, the Renaissance and up to the French Revolution at which time they were expelled, the buildings partly demolished and sold as "National Property." For the first time in 800 years, the plateau was deserted. Nearly a century would pass before the religious community would be revived, monks reinstalled and the first, timid reconstruction work carried out.
For most of the twentieth century, the monastic community—at times reduced to a single member!—lived on the half-ruined, half-rebuilt premises. While Ganagobie was drawn into deeper and deeper solitude, other monks belonging to the same Benedictine order were facing a different problem: their Abbey at Hautecombe in Savoy, the burial place for Italian kings, was being overwhelmed by tourists. By the mid-1980s, the situation had become unbearable: the Benedictine monks at Hautecombe, for whom silence and quietude was so essential, decided to move to Ganagobie.
"We spent five years cleaning up the ruins and rebuilding," explains Dom Michel Pascal, abbot at the time of the community. "Thanks to a recently passed law, we managed to get funds from private companies and launch a real restoration."
Ganagobie now is very much like it was in the late High Middle Ages. The 12th century cloister has been reconstructed based on the few surviving arches, and the old church's 72 square foot mosaic and its bestiary of fabulous animals, the largest in France, has been beautifully restored.
Although living according to community rules formulated more than fifteen centuries ago, the twelve monks of Ganagobie are men of the twenty-first century. They use cell phones, have email addresses and surf the internet. And when faced with the replacement of the church's long-gone stained glass windows, they chose a resolutely contemporary option: they turned to a Dominican monk, the famed Korean-born artist Kim En Jung.
Father Kim spent several weeks at Ganagobie studying the way light penetrated the church nave at different hours of the day. Back at his workshop in Chartres—a stained-glass world capital if there is one—he used enamel and glass-powder baking techniques to produce nine windows, completing his work in 2006.
"I groped my way through the colours as one gropes his way to Paradise," says the artist. In sharp contrast with the thousand-year-old stones of the church walls, his work has brought a final touch to the centuries-long process of restoring Ganagobie.
The question of how to improve control of edge localized modes (ELMs) and the vertical stability of the ITER plasma will be one of the key issues addressed in next week's meeting of the ITER Science and Technology Advisory Committee (STAC). And there will be good news to discuss. In the six short months since the Preliminary Design Review performed in October last year, the in-vessel coil design team led by the Princeton Plasma Physics Laboratory (PPPL) worked with two suppliers from Canada and China to fabricate the largest stainless sheath mineral insulated conductor (SSMIC) ever produced in the world.
"Because of their proximity to the plasma, conductors with conventional insulation schemes were not an option for the in-vessel coils," says Edward Daly, the mechanical engineer who led the design efforts. The team therefore decided to choose SSMIC for its ability to withstand ITER's high radiation and bake-out temperatures of 200 °C.
The sheer scale required for the ELM and vertical stability coils in ITER, however, is much larger than anything produced previously. In June, contracts were awarded to the Institute of Plasma Physics at the Chinese Academy of Science (ASIPP) based in Hefei, China and to Tyco Thermal Controls, Ltd in Ontario, Canada, who both developed prototypes within four months. Once received at PPPL, the prototypes were cut, pushed, pulled, bent, heated, electrified, sliced and x-rayed to evaluate their mechanical and electrical properties.
"In general, the conductor samples performed as we had hoped and expected," says Ed Daly. "There were no show-stoppers, but there is still work to do." The results will be used in the final design and prototyping phase, planned to start in July. ASIPP has expressed interest in manufacturing these coils and has proposed collaboration with PPPL.
ITER's in-vessel coils—another example of world-spanning cooperation.