More info under http://www.jt60sa.org
As part of a “Broader Approach” to accelerate the development of nuclear fusion as a source of electrical power, Europe and Japan identified three major projects to be carried out jointly in Japan, complementing the construction and operation of ITER in France. These three projects are the further development of planning for the construction of a materials test facility (IFMIF), the establishment of an international centre for studies of fusion technology, remote operation and plasma simulation, directed towards the construction of the demonstration electricity generating plant (DEMO) that will follow ITER (IFERC), and the construction and operation of an advanced superconducting tokamak (AST) to act as a satellite tokamak to ITER during its operation. This latter device, a replacement for the JT-60U experiment in Naka, and re-using the site buildings, auxiliaries, neutral beams, and some power supplies, is now known as JT-60SA (SA = super, advanced).
The mission of JT-60SA is to contribute to the early realization of fusion energy by addressing key physics issues for ITER and DEMO. It is a fully superconducting tokamak capable of confining high-temperature (100 million degree) deuterium plasmas, equivalent to achieving plasma energy balance if 50/50 deuterium/tritium were used. It is designed to help optimise the plasma configurations for ITER and DEMO, and has a large amount of power available for plasma heating and current drive, from both positive and negative ion neutral beams, as well as electron cyclotron resonance radio-frequency heating. It will typically operate for 100 s pulses once per hour, subjecting water-cooled divertors to maximum heat fluxes of 15MW/m2. The machine will be able to explore full non-inductive steady-state operation.
Deuterium is used as a fuel because it mimics well the behaviour of a reacting deuterium-tritium plasma in a real power reactor or ITER, without generating large amounts of heat or neutrons. The reaction produces some neutrons directly, plus reactions with tritium, a by-product of one branch of the DD reaction. JT-60SA thus slowly will become radioactive in use, and remote handling of systems near the plasma must be planned.
A conceptual design for the device was prepared in 2005, describing the components and operating parameters. The present design has the following main parameters (those of ITER are shown for comparison).
JT-60SA ITER Major radius (m) 2.96 ~6.2 Minor radius (m) 1.18 <2.0 Plasma current (MA) 5.5 <15 On-axis toroidal field 2.25/NbTi <5.3/Nb3Sn (T)/TF conductor Plasma elongation 1.95 <1.8 Plasma triangularity 0.53 <0.5 Plasma volume (m3) 132 ~840 Inductive pulse length (s) 100 >400
JT-60SA is financed jointly by Europe and Japan. Europe contributes the toroidal field coils, their cold test facility, high temperature superconductor current leads, the main cryostat shell and machine gravity support, the cryoplant and part of the magnet pulsed power supplies, and some radio-frequency power supplies. Japan contributes the rest - poloidal field coils, vessel and in-vessel components, basic power supplies, thermal shields, cryostat port extensions, assembly, disassembly and remote handling, heating systems upgrade, water cooling system upgrade, and diagnostics and control system upgrade.
The Project is carried out by an international Integrated Project Team, composed of a Project Team, which manages a Japanese and a European Home Team. The Home Teams manage the technical specification of components, and their subsequent procurement and delivery to the construction site at Naka. For Japan the Home Team is located in Naka, whereas for Europe the Home Team HQ is in Garching, but members of the team are distributed at institutions in Cadarache, Saclay, Grenoble, Frascati, Padua, Karlsruhe, Brussels and Madrid. A Project Committee advises the Steering Committee for the Broader Approach Agreement about the Project status.
Procurement is formally undertaken by two "implementing Agencies", the Japan Atomic Energy Agency (JAEA) for Japan, and Fusion for Energy (F4E) for Europe. Procurement arrangements for each major item of procurement are concluded between these two bodies and the Project Team, with the involvement of the European and Japanese Home Teams. European procurement for JT-60SA in practice is carried out through voluntary contributions from a number of countries within Euratom through their own institutions, as well as by Euratom itself, through F4E.
The current schedule envisages tokamak assembly starting in 2013 and being completed in 2018, with first plasma in 2019.