A new report by the National Academies of Sciences Engineering and Medicine (NAS), highlights the potential drawbacks if the US were to withdraw from the ITER project – a large international burning plasma experiment.

Despite some budget constraints and shortfalls in recent years, no such decision has been made and the US remains in the project, however the NAS Committee has been charged with investigating, from a scientific and strategic viewpoint, the best way forward for US fusion research including the study of a controlled burning plasma. The Committee has been asked to evaluate the implications of doing this in two ways: if the US remains in the ITER project, and also if the US were to pursue an independent pathway.

The NAS Committee fears that if the decision was made for the US to withdarw, it could isolate scientists from the international effort and require a new domestic approach to study fusion. This report is the first in a two-phase study examining the state and potential of magnetic fusion research in the US and providing guidance on a long-term strategy for the field.

A burning plasma – an ionized gas like the sun and stars heated by fusion reactions – is a key requirement to make fusion energy. A magnetic fusion reactor can be thought of as a miniature sun confined inside a vessel. As an energy source, it has environmental advantages and its fuel is abundant, extracted from sea water. This area of interdisciplinary research results in technological and scientific achievements touching many aspects of everyday life and leads to new insights in related fields such as optics, fluid mechanics, and astrophysics.

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So far, the US fusion energy science programme under the US Department of Energy has made leading advances in burning plasma science. For example, theoretical and computational models have substantially improved control of plasma stability, predicting plasma confinement, and enhancing fusion energy performance, and new techniques have been developed to avoid and mitigate transient events, which can erode plasma-facing materials in the experiment chamber. The overall understanding of burning plasma science has progressed significantly as well. If the US continues to participate in ITER, scientists within the country are also expected to make leading contributions to the study of fusion energy at the power plant scale, the report says.

Currently, the other parties involved in the ITER project – China, the European Union, India, Japan, the Republic of Korea and Russia – have developed national strategic plans for fusion energy demonstration, but the US does not have such a plan, the report says. Without a long-term vision, the US risks being overtaken as other partners advance the science and technology required to deliver fusion energy, said the committee that conducted the study and wrote the report. By adopting a national plan, the US has the potential to support strategic funding decisions and priorities within the national programme and foster innovation toward commercially-viable fusion reactor designs.

The report also calls attention to the need for more research to improve and fully enable the fusion power system, in addition to the ITER project. This research will help develop fusion energy devices that address the remaining science and technology challenges and demonstrate innovative solutions that lead to a reduced size, lower cost, full-scale power source, the report says.

The study was sponsored by the US Department of Energy. The National Academies of Sciences, Engineering, and Medicine are private, non-profit institutions that provide independent, objective analysis and advice to the nation to solve complex problems and inform public policy decisions related to science, technology, and medicine. They operate under an 1863 congressional charter to the National Academy of Sciences, signed by President Lincoln.