There are large dimensions in fusion science. European and Japanese researchers recently experienced them physically. Whilst coming together for an update meeting at the construction site of the Japan Torus 60 Super Advanced, they had the opportunity to climb into the captivating interior of the tokamak. The Satellite Tokamak Program is one of three large projects covered by the Broader Approach agreement concluded between the European Atomic Energy Community (Euratom) and Japan. It consists of the construction of the Japanese Torus 60 Super Advanced (JT-60SA): a completely new load assembly replacing the original JT-60 site in Naka in Japan.

Fusion for Energy and EUROfusion

Fusion for Energy (F4E) is the Domestic Agency charged with implementing the project within Europe with the support of CEA (France), CIEMAT (Spain), ENEA (Italy), KIT (Germany) and SCK-CEN (Belgium). Together with their Japanese counterpart (QST, previously JAEA),they jointly form the JT-60SA Integrated Project Team. EUROfusion as part of this team strongly supports the “Physics Unit” and defines the experimental research plan of the device.

(from left to right)  Darren McDonald (EUROfusion), Elena de la Luna (CIEMAT), Jeronimo Garcia (CEA), Gerardo Giruzzi (CEA and Workpackage Leader), Mathias Dibon (MPG), and Valerie Lamaison who is from CEA but currently based at Naka and working on the cryo-system. Picture: QST

Picture: QST

A project on schedule

Overall the JT-60SA project is on schedule for the first shot in 2019. “This is not only thanks to good preparation of the initial design and technical specifications, but also to the efficient cooperation which was established from the onset, both with Japan, as well as within Europe”, says Pietro Barabaschi, F4E’s European Project Leader for JT-60SA.

Waiting to be shipped

JT-60SA recently achieved a major milestone in the successful testing of its first Toroidal Field (TF) coil which is currently being shipped to Japan. Moreover, the cryostat base, the cryoplant, the quench protection circuit (QPC), the lower Equilibrium Field coils, and the vacuum vessel thermal shield have been already installed. All but one segment of the vacuum vessel, the heart of the JT-60SA, have been positioned and welded into place. In May this year, scientists took the opportunity to slip in through this current gap to explore what has been assembled so far.

One coil per month

What remains to be done until the entire vacuum vessel is completed, is the sliding of the 16 Toroidal Field coils into place on the assembled segments. The last Vacuum Vessel segment will be positioned, and the remaining two TF coils “threaded” into place. French and Italian companies produce the TF coils. They will be delivered to the Naka site, at a typical rate of one per month, from now until the end of 2017.

WHY JT-60SA?

Why do Europe and Japan need to build an additional huge tokamak while there is JET? Darren McDonald, EUROfusion’s ITER Physics Deputy Leader has the answer: “To be economically viable, fusion power plants will need long pulse or even steady state operation. ITER must demonstrate such operation. To assist ITER, long pulse or steady state operation must first be developed on a JET class device. So, we need a machine which, unlike JET, is capable of running long high performance plasmas. JT-60SA is that machine. The key components are its superconducting magnets and active cooling systems.”

For basic information have a look at the article ‘Planning the research programme for JT-60SA’ in Fusion in Europe 2/2014 https://www.euro-fusion.org/newsletter/planning-the-research-programme-for-jt-60sa