Fusion research today

In the fifty years that research on nuclear fusion has been carried out, enormous scientific and technological progress has been made. Fusion scientists now manipulate plasmas of hundreds of millions of degrees, in fusion devices on an industrial scale.

JET - The Joint European Torus

JET, based in Culham, Great Britain, is the central research facility of the European Fusion Programme. The focusing of significant European fusion research funding on JET has made it the pre-eminent fusion facility in the world and allowed Europe to take major strides in fusion research. JET is complemented by a number of specialized smaller devices run by more than twenty individual EU member states. The largest tokamak experiments outside Europe are the Japanese tokamak JT-60 and the American TFTR device in Princeton.
JET was approved in 1974, began operations in 1983, and met its planned operational goals on schedule in 1990. Since then, a new scientific programme has started, and JET now serves as a research facility hosting a large number of international research efforts.

Figure 1: A look inside the plasma vessel of the Joint European Torus (JET). JET is located in Culham, GB.

JET has produced significant fusion power in deuterium/tritium plasmas - up to 16 MW - in the short pulses characteristic of existing experimental devices. "Break-even" conditions, where the fusion output power equals the external input power required to heat the plasma, were almost reached. Moreover, JET has demonstrated that fusion devices can be operated safely with tritium fuel and that radioactive structures can be maintenanced and modified using remote handling techniques.

The future of fusion research

Although it is the largest in the fusion family, the Joint European Torus (JET) is still too small to generate more energy than is put in: to generate 16MW of fusion power in JET, 25 MW is needed as input. There is a simple physical principle behind this: small things cool down quicker than large things - soup in a spoon cools down quicker than soup in a large bowl. That is why it seems logical to construct a larger device, in which it should be easier to keep a plasma hot. The next step in fusion research is ITER, which has twice the linear size as JET. ITER is designed to generate 500 MW fusion power, ten times more than is needed to keep the fusion plasma in the right condition.

The next step: ITER

ITER is a large scale, international experiment that should demonstrate the scientific and technological feasibility of using fusion as an energy source on earth. ITER will allow the study of plasmas in conditions similar to those expected in a electricity-generating fusion power plant. It will also test a number of key technologies for fusion including the heating, control, diagnostic and remote maintenance that are expected to be needed for a real fusion power station. Extensive information on ITER can be found in the ITER section of this website, and on the homepage of the ITER-project.

Figure 2:The ITER-device. The man in the bottom indicates the scale.

ITER started in the 80ies as an initiative of the former presidents Reagan and Gorbatsjov; the current partners in the project are the European Union, Japan, the Russian Federation, China, Korea, India, and the USA, which means that more than half of the global population is represented in the project.
ITER will be a machine of the tokamak type in which the torus-shaped fusion plasma is confined by strong magnetic fields (see illustration). Compared with current conceptual designs for future fusion power plants, ITER will include most of the necessary technology, but will be of slightly smaller dimensions and will operate at about one-fifth of the power output level.

Towards a power plant: DEMO

ITER is not an end in itself: it is the bridge toward a first demonstration power plant that will deliver large-scale electrical power to the grid. The long-term aim of fusion research and development in Europe is to create power station prototypes demonstrating operational safety, environmental compatibility, and economic viability.
The strategy to achieve this long-term aim includes a number of different elements: first of all the development of ITER, followed by a demonstration reactor called DEMO, which will demonstrate large-scale electrical power production. DEMO will be designed using the lessons from ITER. The expectation is that after DEMO, the first commercial fusion power stations can be constructed.