Fusion in Europe and the World-Wide Strategy

Historical Background

The European Union's current Fusion Programme has its origin in the Euratom Treaty (1957), under Article 4 of which the Commission is responsible for carrying out research in certain fields including the «study of fusion, with particular reference to the behaviour of an ionised plasma under the action of electromagnetic forces and to the thermodynamics of extremely high temperatures». Controlled thermonuclear fusion by magnetic confinement thus became a European field of research; thereafter, national fusion research activities were brought together in a single European programme.

In the 1950s and 1960s, many lines of development were explored and tested to ascertain their value in terms of plasma confinement quality. With few exceptions these were small-scale experiments : the plasma was very short-lived, owing to macroscopic instabilities and impurities affected its behaviour. It became clear that a larger-scale programme, with bigger equipment, would be needed to improve plasma performance. The World's largest and most powerful tokamak project was launched : the JET («Joint European Torus») Joint Undertaking. Operation of JET started in 1983 and Europe thus became the world leader in fusion research.

Strategy and Implementation

The long-term objective of the Community project, which integrates all magnetic confinement fusion research performed in the EU Member States (plus Switzerland), is the joint construction of safe and environment-friendly prototype reactors, leading to the construction of economically viable power stations meeting the needs of the potential users.

	European Strategy for Research into «Magnetic Fusion».

World-wide there are four major fusion programmes of similar importance : those of Euratom, Japan, Russia and the U.S.A. All four are working towards the same long-term objective, but progress will require decades.

In Europe, after JET, the plan is first to build an experimental reactor (to be known as «Next Step») and later a demonstration reactor («DEMO»).

In 1992, Euratom, Japan, the Russian Federation and the USA signed a quadripartite agreement under which this next stage project is to be carried out jointly. The project (named ITER : International Thermonuclear Experimental Reactor) aims to demonstrate the scientific and technological feasibility of thermonuclear fusion for peaceful purposes by achieving and maintaining ignition in deuterium-tritium plasmas over long pulse times and ultimately in steady-state. It should demonstrate the integration of the technologies essential for a fusion power plant and make it possible to test components under high heat and neutron fluxes.

ITER is a tokamak design, with geometry similar to that of JET - which produces, together with other tokamaks, one of the most reliable current data base. The research, development and technology work, and some of the actual design work, is being carried out by the four partners' teams (the Home Teams). The rest of the design work and the integration of all contributions in a single coherent project are the responsibility of a Joint Central Team made up of staff from the four partners, distributed between three Joint Work Sites of equal importance. These are :

• Garching (European Union) for the reactor core
• Naka (Japan) for the magnets, structures and nuclear components
• San Diego (United States) for the design and integration.

Moscow (Russian Federation) is home to the official headquarters of the ITER Council.

The main (though as yet preliminary) characteristics of ITER are as follows :

According to current plans (1994), ITER should become operational in the first decade of the next century, but not until the following stage (DEMO) will the project start to produce electricity. A commercial fusion reactor might be ready for use in the middle of the next century.

ITER Configuration 1993

Cutaway view of ITER (computer-assisted design) (ITER-EDA, San Diego, USA).

Tore Supra being assembled (Euratom-CEA, Cadarache, France). The various components of the cryostat which insulates the superconducting coil from the external environment can be seen on this section : the thick housing for the coil, which must be cooled to 4.5 deg K ; on either side the thin thermal screen, to be cooled to 80 deg K, designed to minimize heat exchange by radiation ; on the outside, the double-walled containment designed to keep the whole apparatus airtight once it has been evacuated.