Europe pools experimental capacities to focus efforts on realising fusion electricity

The recently started experimental campaign on Medium-Size Tokamaks (MST) is probably the most visible example of how the European Fusion Programme has transformed its research into an integrated, goal-oriented activity. Three Research Units – IPP, CCFE and CRPP – make experimental time directly available to EUROfusion, a consortium which is currently being formed. In return, EUROfusion provides funding to their machines. “Within our programme these devices will be exploited on the basis of the roadmap’s defined missions,” explains Darren McDonald, Acting Head of EUROfusion’s ITER Physics Department. While JET remains the central device of the EUROfusion Programme, the additional tokamaks enable experiments that cannot be done on JET, they complement and confirm JET results and they broaden the experimental database. Moreover, the Medium-Size Tokamaks provide the basis for a stepped approach: Testing plasma regimes of operation, for instance, on ASDEX Upgrade and then scaling them up for JET provides valuable information about extrapolating experimental results from JET to ITER and DEMO. Moreover, the Programme will benefit from the increased experimental time and enable more European researchers access to a fusion experiment. The participating machines will benefit from the competences that the incoming scientists bring with them. The main objectives of the MST Programme are the investigation of plasma regimes of operation for ITER and of novel concepts that help reducing the heat loads at the divertor for future fusion devices.

Implementing the spirit of JET

Piero Martin from the Italian Research Unit RFX leads the Medium-Size Tokamak Task Force (MST1). “Two hundred and thirty-three scientists, twenty-four laboratories, three tokamaks in three different countries. You certainly don’t miss diversity in this job. But this indeed is what makes it fun and interesting,“ he says. Together with the Deputy Task Force Leaders – Marc Beurskens (CCFE), Stefano Coda (CRPP), Thomas Eich (IPP) and Hendrik Meyer (CCFE) – and with the EUROfusion responsible officer, Marie-Line Mayoral, he designs the MST1 campaigns – advised, of course, by the machine operators. The interest in the community was high, he recalls: “For the 2014 ASDEX Upgrade campaign, we received 3000 proposals for plasma discharges. Together with the proponents and by exploiting synergies we were able to realise most of the key proposals with about 600 plasma discharges.”
Transforming a nationally managed experiment into a partly shared facility is an organisational challenge. “MST is a new way of thinking,” says Darren, “A local machine can be operated more flexibly, because the scientists are more or less always on site. When researchers come from all over Europe, any changes to the schedule can affect the travel plans of dozens of people. It can all be dealt with, but it requires good organisation.” Many of those organising and doing the experiments, can use their experience from working at JET. JET and its way to organise joint research programmes (see page 15) serve as a blueprint for the MST1 campaigns.

The year 2014 belongs to ASDEX Upgrade

In February, the MST1 campaign successfully started on ASDEX Upgrade and will run for about six months. Much of the programme is dedicated to optimising the baseline and hybrid scenarios in the presence of metal walls, including the control of plasma instabilities and impurities as well as investigating detached divertor configurations. ASDEX Upgrade is the only machine available to EUROfusion in 2014, as TCV and MAST are undergoing upgrades. Therefore, 40 out of its planned 80 experimentation days are available to the consortium. Scientists from all over Europe conduct the experiments. Most come a few weeks to participate in specific experiments, but a small number will visit for the whole campaign to support their critical diagnostic systems. Even though research on ASDEX Upgrade has always been conducted within an international framework, this new scheme brought considerable changes, says Arne Kallenbach, technical project leader of the device: “We had to provide additional offices and meeting rooms, including all the IT infrastructure. Every Monday, ten or more new scientists turn up and need an office, keys, access to the intranet, attend the safety instructions, fill out the proper forms and so on. It was a huge challenge to organise all that, but now things are settling into a routine.”

TCV is getting ready for 2015

Deputy Task Force Leader Stefano Coda from CRPP will probably watch closely how IPP organises the campaign. In 2015, the CRPP tokamak TCV will enter the European Programme. What kind of advice would his colleagues give him? “Start planning the infrastructure as early as possible,“ says Arne Kallenbach. “Good communication is important. Keep talking to the EUROfusion Programme Management Unit,“ suggests Darren McDonald. Piero Martin is confident: “There will surely be new challenges, but the TCV team is so experienced that we will definitely build a successful campaign.”

The MST1 devices:
Operated by IPP in Germany, ASDEX Upgrade is equipped with a tungsten wall (one of the planned ITER wall materials) and it can create ITER-like high power loads at the reactor wall. It scales up to JET, which enables a stepped approach to the development of ITER plasma regimes of operation.
The tokamak TCV allows very flexible magnetic configurations. It is operated by CRPP in Switzerland. During 2014 TCV is undergoing a major upgrade in heating power. From 2015 on it will investigate proof of principle concepts of snowflake divertor configurations, which could reduce the heat loads at this area of the reactor wall. (see FiE 3/2012) The spherical tokamak MAST operated by CCFE in the UK is being upgraded to investigate especially the super-X divertor – a magnetic configuration that spreads the heat loads at the divertor area. MAST-Upgrade campaigns are planned for 2016.