Fusion energy production in ITER requires the achievement of high pressure plasmas in high energy confinement mode (H-mode). This confinement mode is characterized by the formation of very steep plasma pressure profiles at the edge of the plasma that lead to periodic bursts of energy being expelled by the plasma (typically a small percentage of the total plasma energy) called ELMs (Edge Localized Modes).

Although ELMs have no impact for the vacuum vessel, due  to the large plasma energy of ITER plasmas the energy bursts caused by ELMs can lead to an accelerated erosion of the divertor and first wall components in contact with the plasma.

 This could lead to a more frequent replacement than foreseen in ITER. In addition, the eroded atoms can penetrate and contaminate the plasma thus decreasing the energy production.

ELM control is required for the achievement of fusion energy in ITER. Two schemes are foreseen to minimize the impact of ELMs—pellet injection and in-vessel ELM control coils.

Understanding the magnitude and structure of the ELM energy bursts and quantifying the effectiveness of ELM control schemes is an active field of research where significant progress has taken place recently. Simulations of ELMs in ITER with the non-linear code JOREK have shown that there are two mechanisms for the flow of energy from the plasma to the components in contact with the plasma during ELMs (see image above): one is the loss of energy by the plasma in the strongly perturbed edge magnetic field during the ELM (conductive losses); the other is the expulsion of plasma filaments (analogous to solar flares) which move radially away from the plasma towards the wall.

JOREK simulations show that for small ELM energy losses the dominant mechanism is the expulsion of filaments and that this energy is deposited over a large area of the divertor and wall. This allows more room for ELM control in ITER than originally anticipated.

Progress on ELM characterization and ELM control has also come from the experimental side. ELM avoidance using 3-D field magnetic field perturbations, which will be provided in ITER by a set of 27 in-vessel coils, has now been achieved in a large number of experimental devices. Results span the range of densities and collisionalities expected at the ITER plasma edge, although ITER values cannot be achieved for both parameters simultaneously (these can only be achieved in ITER itself). While understanding of the detailed physics processes that lead to the avoidance of ELMs with 3-D magnetic field perturbations remains elusive, ELM avoidance using this scheme has now been observed in numerous experimental devices. This increases our confidence in the viability of this ELM control scheme for ITER.

Recently, there have also been major advances on the second ELM control scheme foreseen for ITER, which utilizes the controlled triggering of the ELM bursts by the injection of small frozen deuterium pellets. Experiments in the DIII-D tokamak in which very small pellets were injected have demonstrated for the first time that this technique can be used to increase the frequency of the ELM bursts, and to decrease the magnitude of the fluxes that they deposit, by more than a factor of ten (a factor of 30 may be required in ITER). In these experiments, detrimental effects on the plasma energy confinement were modest. This is a major advance from previous results in JET, ASDEX-Upgrade and DIII-D, where factors of only 2-5 were achieved in ELM frequency, but, in some cases, with noticeable detrimental effects on plasma energy confinement.

The DIII-D experimental results have been reproduced with the JOREK code, which has subsequently been applied to evaluate the pellet characteristics (size and velocity of injection) required in ITER to achieve controlled triggering of ELMs (see image at left). The JOREK results show that these requirements are met with the specifications foreseen for the ITER pellet injection system and pellet injection geometry. The associated fuel reprocessing requirements are also consistent with the specifications of the ITER tritium reprocessing plant.

Although uncertainties remain regarding ELMs and the application of the ELM control schemes to ITER, recent progress in this area has substantially increased our confidence that ITER is equipped with the appropriate tools to achieve the ELM control level required for the achievement of significant fusion energy production.

The last time an aerial photo survey was conducted of the ITER site, in September 2011*, the lower basemat had yet to be poured in the Tokamak Seismic Pit; cladding and roofing operations were underway on the Poloidal Field Coils Winding Facility; and windows were being installed at ITER Headquarters.

A year and a half later, a four-hectare electrical switchyard is in place and 500 people work from the completed Headquarters building. Preparatory works have just begun for the Tokamak Complex basemat (the B2 slab) that will rest atop the Seismic Pit's 493 concrete columns (plinths) and pads.

Whereas in 2011, vast expanses of barren land still existed between the different work areas on the platform, this new series of photographs, taken two weeks ago, shows a much different landscape: mounds of earth, trenches, and material and vehicle storage areas now occupy most of the available space between the buildings.

In the Seismic Pit, the radial pattern of the plinths is clearly visible from the air. Nearby, the completed sections of the Assembly Building foundation slab reflect the mid-afternoon winter sun. From the Headquarters Building, long shadows extend almost all the way to the deserted parking lot (the photograph was taken on a Saturday). On the "green" rooftops of the Access Control Building, the Amphitheatre and the Medical Building, the sedum plants wear their winter colour—they will turn from red to green in the summer and from green to yellow in the fall.

Photographer Matthieu Colin carried out the latest ITER aerial campaign from an ultralight aircraft flying at an altitude of 500-900 metres. (The September 2011 photographs had been taken from a helium-filled balloon hovering at 70-100 metres above ground.)

 

Close to 900 people—a record for the ITER canteen—attended Japan Day on Monday 4 March, the latest National Day celebration at the ITER Organization.

ITER's celebration coincided with a Japanese tradition called Hinamatsuri, or Girls' Festival, celebrated on 3 March—a day to pray for a young girl's growth and happiness. In the weeks leading up to this festival, most families with girls display ornamental dolls representing the Emperor, Empress, attendants, and musicians in the traditional court dress of the Heian period, and arranged on a five- or seven-tiered stand covered with a red carpet.

At the luncheon attended by the Consul General of Japan in Marseille, Masaaki Sato, and his wife, traditional Japanese dishes were prepared by ITER's Sodexo food service: kenchin soup and either an oyako or tamago rice bowl.

The ITER band accompanied singers Michiya Shimada, Sachiko Ishizaka, and Arata Nishimura from the ITER Organization and Masao Ishikawa (JAEA) in a selection of Japanese pop and folk tunes known in the West as "Sukiyaki" songs, that inspired some members of the assembly to join in.

Fusion research is deeply indebted to Australia: it was the Australian Mark Oliphant who, under the guidance of Ernest Rutherford, realized the first fusion reaction at Cambridge's Clarendon Laboratory in 1933, and it was in Australia where the only tokamaks outside the Soviet Union operated between 1964 and 1969.

Over the past half-century, the country's small but active fusion community has developed a strong reputation, carrying out seminal theoretical work in plasma physics, developing significant plasma diagnostic innovations and making important contributions to fusion materials research.

Many Australian fusion physicists are closely associated to the ITER project. While Australia is not an official Member, these physicists are eager to see their country engage with it. As yet, no formal institutional collaboration has been established.

On his visit to ITER, last September, Australian National University physicist Matthew Hole, who chairs the Australian ITER Forum, shared his hopes for Australia to become more involved.  "ITER," he said, "will define the fusion research program for at least the next generation. We're keen to be part of that enterprise ..."

How could Australia be more closely associated to ITER? The question was at the centre of the "very useful conversations" that Adi Paterson, the Chief Executive Officer of the Australian Nuclear Science and Technology Organisation (ANSTO), had with the ITER management when he visited here on 20 February.

"A project the size and scope of ITER cannot be limited to only seven Members," explains Paterson. "ITER has to think of countries like Australia that can connect to the project in a very effective manner outside of a full membership arrangement and potentially form a new model of engagement."

In this context, ANSTO has an important role to play. "My job is to help define and implement a coherent strategy and assist in strengthening the fusion community at home" adds Paterson. "We need to initiate exchanges, develop knowledge on the real questions of diagnostics, 3D fields, energetic particles, collision cross-sections, materials, neutronics..."

The "model of engagement" doesn't exist yet, but both sides are eager to create one. Seeing the reality of the project's progress comforted Paterson in his determination. Along with the obvious progress of construction and of components manufacturing, what makes ITER real in the eye of ANSTO's CEO is "the milestone that was accomplished last November. When the nuclear safety regulator says 'you can carry on', this is a huge accolade, and one that brought confidence to the whole fusion community worldwide."