Science Challenges and Opportunities
ITER poses challenges for magnetic fusion energy science and offers opportunities — some unique — to address fusion science issues in the ‘burning plasma regime’. The threshold for entry into this alpha-heating-dominated regime corresponds to a fusion power gain Q equal to 5. ITER and other proposed ‘burning plasma experiments’ target Q = 10 as their nominal objective.

The alpha heating needed for Q > 5 has not yet been achieved. A new ‘next step’ experiment such as ITER is needed. But investigations in present experiments have identified the ‘science challenges’ that must overcome to reach the burning plasma regime. Given success in surmounting these ‘enabling’ challenges, ITER will then provide certain burning-plasma-unique ‘science opportunities’ for obtaining the definitive plasma and materials science understanding need for a future power-producing fusion reactor.

Fusion Science in ITER: Challenges
and Opportunities
ITER science challenges and opportunities are detailed in the topical links below. The organization follows the topical categories used for the ITER Physics Basis [Nuclear Fusion 39 (1999), pp 2137-2638]. This full-issue article presents overview and topically-organized documentation and discussion of the fusion science bases for ITER.

Color indicates burning plasma ‘uniqueness’. Blue topics are not inherently affected by plasma self-heating and/or the presence of energetic alpha particles. The science aspects of these topics can, in principle, be understood without a need for explicit alpha heating. In contrast, red topics do depend critically on the presence of alphas and/or the attainment of alpha-dominated heating. A new facility (eg., ITER) is needed for their resolution (as challenges) and for their science study (as opportunities). Such a facility will also provide a unique opportunity for integrated topical science investigations – with all parameters attained simultaneously – of reactor-like burning plasmas.

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