On July 11, ITER Director General Osamu Motojima came to JET to lay the foundation for the intensified collaboration between the two experiments. Motojima-san met with EFDA Leader Francesco Romanelli to review the recent experiments with the ITER-Like-Wall and to discuss future collaborative work on JET.

“We strongly welcome ITER’s interest in JET” said Romanelli. “In the view of generating results that support ITER, it is our aim to make JET available also for scientists beyond Europe.” With Motojima were David Campbell (ITER Director of Plasma Operation) and Alberto Loarte (ITER senior scientist). “We are keen to work closely with the JET team on matters like disruptions or melting studies, “ said David Campbell, who spoke to staff at JET about the science challenges for ITER. “The work carried out here is extremely impressive and will be important for the exploitation of ITER. I encourage you to carry on along the same path.”

Back in the 90s, results from JET experiments provided the basis for the design of ITER. Now that ITER is being built, the JET experiments aid the process of designing the ITER physics programme and preparing ITER operation. JET’s size, its capability to operate with tritium and its recently installed ITER-Like-Wall, make it the best machine to answer ITER questions. “ITER depends on the success of JET” Director General Motojima said. “The results that have been achieved with the new wall in such a short time are both impressive and encouraging”.

Taking collaboration to a new level

ITER and JET maintain close ties: For years, ITER representatives have attended the JET planning meetings and the JET Associates have aligned their experimental programme to meet the needs of ITER. Now that JET experiments are increasingly dedicated towards providing answers for creating ITER, ITER scientists should play an active role in them. To provide a legal framework for this participation, the ITER Organization will join the IEA Implementing Agreement for Cooperation on Tokamak Programmes. These types of contract form the basis for international collaboration on JET and regulate issues such as the exchange of personnel, access to data, publication rules and intellectual property rights. “This is a very important step,” explained EFDA Senior Advisor Duarte Borba. “To make sure that our experiments provide the right results to ITER, we need to involve ITER scientists early on. We want them to participate in the definition and execution of the experiments as well as in the analysis of the results.”

Investigating ITER cost cuts

One key experiment planned for next year is to investigate how deliberately melted tungsten tiles affect JET operation. The outcome of this exercise could help ITER save 400 million euros. According to current plans, ITER will start operation with a carbon divertor and change over to tungsten for the deuterium-tritium experiments. The reason for this is the assumption that carbon will be more forgiving during the start-up phase. To cut ITER costs, the Director General proposed starting with tungsten immediately. The ITER council has now granted time to work on the technology and assess the risks that accidental melting of tungsten tiles may pose for ITER operation. The melting experiments JET is to carry out will provide key answers to that question.

Saving time for ITER

JET is also the only facility capable of running deuterium-tritium (D-T) experiments. This allows the investigation of specific physics related to D-T regimes of operation, such as how mitigation techniques work for harmful ELM-instabilities, a process which will shorten the learning curve at ITER. Having ITER scientists on-site at JET will save time, too, said Lorne Horton, who heads the EFDA JET Department. “An extended D-T campaign at JET is an ideal training ground for ITER personnel. ITER has an aggressive schedule and the scientific teams do not have much time to get used to each other or to the procedures of a nuclear fusion facility.” In his opinion, it would certainly be a head start if part of the team have already worked together. “The independent panel that reviewed JET and the European Fusion programme pointed this out.” Horton continued, “We hope that ITER will recognise that and send us staff and we recommend other ITER partners to do the same.” JET would also be in a position to test hardware for ITER, added Duarte Borba. “In the past, we have always tested new methods on smaller tokamaks, like ASDEX Upgrade or D-III D, and then scaled them up to JET. It makes a lot of sense to do the same for ITER, for instance with the planned mitigation systems for ELM instabilities. Knowing how the systems behave before installing them in ITER saves a lot of time.

Involving ITER partners

JET also promotes the participation of other ITER partners in its programme, Borba continues. “Scientists from the ITER Organization will now be directly involved in JET experiments, but ITER is a group of partners. To make ITER a success, we need to provide these countries with the opportunity to conduct experiments at JET.” One method of doing this may be to implement a system that they have developed for ITER and to carry out preparatory experiments on JET. JET is, for instance, currently engaged in collaboration with India regarding software for charge exchange diagnostic systems. Every collaboration with an ITER partner brings more experts and knowledge to the JET team, also benefiting the European fusion programme. With sufficient collaboration of this type, JET’s role as a hub for fusion knowledge will reach beyond Europe and encompass the whole world.