The next big step in fusion development is to create a plasma that keeps itself hot by the energy released in its own fusion reactions. The ITER international collaboration has developed a design to sustain such a so-called “burning plasma,” generating about 500 megawatts of fusion reactions for approximately 1,000 seconds. To achieve this requires a plasma about twice as large, and also requires the use of superconducting magnets that consume negligible electric power for their operation.
Because of its size and technological complexity, ITER will cost about $5 billion to construct. It is not a commercial power plant, nor even an engineering demonstration plant; it is an experiment that is designed to establish the scientific feasibility of controlled fusion. Sharing its significant cost is one motivation for pursuing it as an international collaboration. But other motivations include the long-term nature of fusion research. ITER will take about 10 years to build. A road map recently developed in the United States for a relatively fast-track to fusion envisages over 30 years before fusion would be sufficiently developed for commercial deployment. Therefore, fusion is a technological grand challenge that is not dominated by short-term economic competition, and is ideal for international cooperation. Indeed, ITER will be one of the largest joint-scientific projects ever undertaken by an international consortium. The present ITER partners are the European Community, Japan, the United States, Russia, China, and South Korea.
The long development time of fusion could be a handicap, though. It serves to discourage some policy-makers from a major commitment to its research, and it breeds skepticism in fusion’s critics. As the earlier ITER engineering design activity neared its end in the mid-1990s, major cuts in the U.S. fusion research budget led to a change of U.S. Department of Energy policy for fusion, and to an eventual pull-out from the ITER project, of which the United States had initially been one of the leaders. With the closure of our largest tokamak and of several smaller experiments, the canceling of a major, planned follow-up device, and deep cuts in funding for other national fusion facilities, the U.S. fusion community recognized that its research program had to be reoriented to focus on the underlying fusion science of plasma physics and related engineering. We did not then have a program that was truly one of fusion energy development. Thankfully, the United States rejoined the ITER project in 2003, but in a much more junior role, reflecting the fact that U.S. fusion research funding is very modest (about $290 million in fiscal year 2006), less than half the level of Europe’s efforts.
The United States still has two world-renowned tokamaks (one of which is at MIT), whose research will be crucial during the ITER construction phase in helping to resolve and prepare for important scientific and technical challenges that ITER faces. It is also important for the United States to maintain fundamental research and innovative initiatives into the basic science of magnetically confined plasmas, which may lead to breakthroughs that eventually enable faster fusion development and more cost-effective fusion systems. But, the U.S. capability in fusion plasma science cannot be sustained without a renewed commitment of resources. The United States 10% share of ITER construction will call for peak expenditures of up to perhaps $150 million per year, mostly for industrial procurements, not research.