What will we learn from ITER?

Abstract

At the time of writing, we are once again at the threshold of an international agreement to go ahead with the construction of the ITER (International Thermonuclear Experimental Reactor) project, uniting the research efforts of Europe, Japan, China, Korea, Russia and the USA. It is very much the hope that at the time of reading, preparations at the construction site, whether in Europe or Japan, will be well underway. The project is extremely ambitious and carries a significant construction cost, roughly 500M€ per year over 10 years of construction. If built in Europe, the likely domestic cost will be 250M€ per year to the European taxpayer, including Switzerland. Although this is of course very large for a scientific research project, it still only represents the sum of 2.5€, or the average price of a small beer in Europe for each taxpayer every year, a much lower cost than many marketing projects. Why spend so much? What will we learn from ITER? These questions have been raised in some academic circles, contesting the size of such an investment in a scientific experiment. We consider it judicious to attempt a reply, addressed to the general physics research community, explaining what will be achieved and especially what lessons will be learned. Is ITER a project in the basic sciences lineage, searching ultimate truths about the nature of the world, or about the origins of our universe? The answer is “No”. Such questions have an essential purity about them, a purity that has always appealed, both to the initiated and to the uninitiated, as representing a noble cause, a scientific golden fleece. The world’s largest accelerators have always received relatively constant support in Europe, in spite of the difficulty the public at large has to grasp the significance of the results obtained, or even understand the questions being addressed. ITER is nonetheless a noble cause, even though its main motivation stems from our increasingly urgent quest for sustainable energy. The nobility resides equally in the physical understanding to be acquired of the complexity of plasmas and in the technical challenges to be met. The requirements for controlled nuclear fusion are potent drivers for advances in physics and technology. This quest has also brought a harvest of fundamental knowledge in physics, in such complex areas as turbulence, magnetohydrodynamics and even material sciences, with implications for apparently unrelated areas such as astrophysics, space physics and industrial plasmas, spawning applications ranging from plasma processing to space propulsion systems, the development of novel materials and superconductors. The ITER project is set to take this endeavour a major step further into uncharted territory. In the following we shall try to remind the reader of the “why ITER?” with a brief introduction and then recall the present state of our research into controlled fusion using magnetic confinement of plasmas. The status today is, simply stated, that we believe that our long-term vision can become reality, but we need to make a leap forwards to demonstrate this. ITER is the long-awaited step needed to take fusion out from the present large laboratory experiment in the direction of a full power station. We shall see that our question “why ITER?” leads to a simple answer “to establish whether our vision can become real”.