“Oh … well … now, that is interesting” – Andrew Kirk lifts his hand to his forehead and stares at the screen. Another shot, a short burst of plasma lasting for less than a second, has just been triggered. On this particular Thursday morning, the ASDEX control room in Garching is crowded with people bending their heads over their laptops or discussing with colleagues. “We expected something like this but … not quite this”, Andrew Kirk muses and rushes back to his laptop.

Three tokamaks and a stellarator

The British scientist from the Culham Centre for Fusion Energy is one of 391 European researchers participating in the EUROfusion medium size tokamak (MST) work package. Within this, ASDEX-Upgrade experiments are set to take place from mid-June 2015 until the end of April 2016. The results of his fusion research have set Kirk’s head spinning are some of the first, but there are many more to come. On behalf of EUROfusion, three tokamaks and one stellarator are about to operate at the same time: Two MSTs, ASDEX-Upgrade in Garching and the Tokamak à Configuration Variable (TCV) in Lausanne, and the Joint European Torus (JET) in Culham will be pulling out all the stops. At the end of this year, a stellarator will also be joining in: Wendelstein 7-X (W7-X).

Andrew Kirk idscusses the outcome of shots at the tokamak ASDEX-Upgrage. (Picture: Anne Purschwitz, EUROfusion)

Andrew Kirk discusses the outcome of shots at the tokamak ASDEX-Upgrage. (Image: EUROfusion)

Four devices designed to meet one goal: ITER

The scientific aims of the 2015 EUROfusion experiments are dedicated to finally demonstrating the feasibility of fusion electricity production by 2050, as described in the European fusion roadmap. ITER is the key step towards this final goal. This certainly applies to the experiments of Kirk, who is involved in the control of Edge Localised Modes (ELMs). “Imagine putting a saucepan of water onto a hob and turning on the heat. Eventually the water will start boiling, turbulences occur at the surface, carrying away precious energy. To keep the energy contained you will use a lid. Under the lid the steam pressure builds up. Depending on the rate of heating, either the pan boils over, which is a plasma disruption or if the heating is not too great, the pressure increases just enough to raise the lid in a cycle of pop-pop-pop – this pressure relaxation is similar to an eruptive instability in tokamaks which we call an ELM”, he explains.

To avoid this constant clattering of the lid, the chef can insert a spoon under the lid allowing a little steam to escape. Andrew and his colleagues use the “stick a spoon in” method which, in scientific terms means the modification of the magnetic surfaces near the edge of the plasma by triggering perturbation in the magnetic field. Hence, after every shot in the tokamak, Kirk checks the screen that hangs from the ceiling in the middle of the ASDEX control room. The graph of density over time and its ups and downs provide important information for the energetic scientist.

Travelling fusion scientists

The simultaneous operations of ASDEX, JET, TCV and W7-X in the second half of 2015 will require fusion scientists to travel all over Europe. It is a credit to the organisational skills of the EUROfusion team that a twoweek postponement of the Garching campaign could smoothly be dealt with by Kirk and the participating colleagues. On a tight schedule, Marie-Line Mayoral and Laura Barrera Orte, the Responsible Officers from the ITER Physics Department meet every Monday afternoon with the MST Task Force Leaders Piero Martin, Thomas Eich, Hendrik Meyer, Stefano Coda and Marc Beurskens to oversee organisation. With the help of Arne Kallenbach, the ASDEX operator, they needed to reschedule the experimental programme in Garching as a result of a diagnostic problem that occurred just shortly before the campaign was due to start.
“Coordinating people is not just a question of logistics. In fact, we rather focus on scientific aspects, making sure that the teams we want are there when they are needed. For this reason, we want to get the best results out of the experimental programme”, says Mayoral. The organisation of the campaign began about a year before the actual 5start. After a call for proposals, the EUROfusion team selected the experiments to be run and the number of shots to be carried out during each of them. Afterwards, the scientists were attached to the respective experimental teams, in accordance with their competencies.

Map with tokamaks JET, TCV, ASDEX-Upgrade and stellarator W 7-X.

EUROfusion map with the location of ASDEX-Upgrade, TCV, JET and Wendelstein 7-X. (Image: EUROfusion)

JET, TCV AND W7-X about to take off

The next facility to take off during the 2015 campaign will be JET, which will focus on preparing for the deuterium-tritium operation for nuclear fusion research. The tokamak TCV in Lausanne restarted operations after a 19-month shutdown during which its vacuum vessel was modified to accommodate its first neutral beam. After the installation of the neutral beam injector, TCV will be operating from early August, in preparation for a campaign starting on 5th of October.
W7-X in Greifswald is also almost ready to rumble. The key element of EUROfusion’s goal is to bring stellarators to maturity as a possible alternative solution for fusion energy . Scheduled for the last half of 2015, the first plasma on this brand new machine and next generation stellarator device is enthusiastically anticipated.

Launching EUROfusion has boosted European fusion research

Bringing together the operations of three European tokamaks and one stellarator will be a major achievement. Thee essential re-organisation of EUROfusion has been necessary to operate the machines and to coordinate the work of the EUROfusion scientists effectively. Following this, JET activities, which were run separately under the former European Fusion Development Agreement, have now been integrated into the ITER Physics Department.

“The Task Force Leaders and Project Leaders, together with the rest of the EUROfusion team, are now using this organisation to perform the required design and development for ITER’s success and the preparation of DEMO,” says Darren McDonald, Deputy Head of EUROfusion’s ITER Physics Department.