The last JT-60SA Toroidal Field coils have arrived in Japan

3.30 pm on Friday 16 February was a significant moment for the JT-60SA project: the last two Toroidal Field (TF) coils needed for the tokamak assembly left – in style – in one of the biggest airplanes in the world from Europe to Japan. Amidst the roar of four jet engines, coil #17 “Isabelle” and coil #20 “Jeanne” (both named after French film stars) lifted off smoothly from Vatry airport, east of Paris, on board an Antonov-124 exclusively chartered by F4E through French transport company, DAHER. “It’s the only plane with a wide enough door as each coil is over 5.5 metres wide on its transport frame,” explains Sam Davis F4E Technical Officer responsible for overseeing the packing and transporting of the TF coils.

The TF coils form the backbone of the JT-60SA tokamak – the container which houses the fusion reaction. It is their magnetic field that provides the primary confinement for the superheated plasma, and the assembly of JT-60SA cannot proceed without them. 16 coils have already been dispatched to the JT-960SA site in Naka, Japan, by ship. “Organisationally speaking, in terms of the division of the work, the TF coils are one of the most complicated systems we have to supply for JT-60SA” says Sam Davis. “It was almost inevitable we would have some delays.  But we do not want our project to be late, so now we have to catch up. We can save over six weeks with this flight”.

Until ITER is finished, JT-60SA will be the largest superconducting tokamak in the world and F4E has led the European contribution to the project for the last 10 years. The TF coils, each 7.5 metres high and 4.5 metres wide, were supplied in partnership with ENEA (Italy) and CEA (France) as part of the Broader Approach agreementbetween Europe and Japan. Packed on their transport frames the two coils make a payload of 64 tonnes – oversized cargo by any standard.

F4E engineers carefully reviewed their packaging in the light of the higher forces that can occur during flight and CEA implemented the necessary enhancements after they had tested the coils and pre-assembled them with their Outer Intercoil Structures in Saclay. The preparation was not without its challenges – with only one week before lift-off, minus temperatures and heavy snow around Paris during the whole week prevented many staff from reaching the Saclay site and trucks were banned from the roads.

After being escorted to the airport, the TF coils were lifted onto an inclined plane assembled in front on the Antonov to allow them to be winched inside through its nose. 33 hours after take-off, having stopped in Turkmenistan and in China for rest and refuelling and having burned 183 tonnes of kerosene, the 19 crew and their precious cargo touched down in Nagoya, Japan. Here the coils were transferred to a barge for transfer to Hitachi port, where all the other large components for JT-60SA enter Japan.

Now in Japan, the focus is on finishing the magnet assembly. The 18^th TF coil will be inserted together with the last 20° sector of the vacuum vessel and its thermal shield. In Europe the two spare coils remain to be tested – and with a little less time pressure the team will take the chance to understand their behaviour a bit better.

With events happening in four time zones, the F4E “crew” accompanying the coils had to get used to working on Zulu time (UTC). A single reference for everyone’s schedule? “It’s not a new idea. We should do it more often!”, laughs Sam Davis. For the JT-60SA team in Europe and Japan the target is clear: first plasma in 2020.

A celebratory event to mark the conclusion of the French contribution with regards to the JT-60SA TF coils was hosted by Daniel Verwaerde, CEA Managing Director and the event was attended by F4E’s Director, Johannes Schwemmer and other high-level representatives from F4E, GE, ENEA, DAHER, as well as the JT-60SA Home Team Project Manager and Leader for Japan’s contribution to the BA project. During the event, Johannes Schwemmer congratulated the participants, “I’m proud to be standing in front of such a high performance team that has made such excellent progress and delivered despite such technical challenges and the massive size of these TF coils”.

See the aeroplane carrying the TF coils landing in Japan: https://www.youtube.com/watch?v=CT2OVEZFNeI