Physics basis for the reference flat-top plasma scenario in the ST–E1 fusion power plant

@article{mcnamara2026physics,
  title = {{Physics basis for the reference flat-top plasma scenario in the ST–E1 fusion power plant}},
  author = {Steven McNamara and S. Abouelazayem and А. И. Алиева and Michail Savvas Anastopoulos Tzanis and J.W. Berkery and A. Yu. Dnestrovskij and A V Dudkovskaia and Filip Janky and Jisung Kang and Nicolas Lopez and E.N.J. Maartensson and Rajesh Maingi and Chris Marsden and Sergei Yu. Medvedev and Andrew Oakleigh Nelson and Vadim Nemytov and J. F. Parisi and Y. Ren and Matthew Robinson and M. Romanelli and A. Scarabosio and Mattia Scarpari and A. D. Sladkomedova and Timothy Stoltzfus-Dueck and Yuichi TAKASE and J. Varje and E. O. Vekshina and C. Wilson and X. Zhang and C. F. B. Zimmermann},
  journal = {Nuclear Fusion},
  year = {2026},
  month = jul,
  doi = {10.1088/1741-4326/ae5f33},
  url = {https://doi.org/10.1088/1741-4326/ae5f33},
  note = {CC BY},
}

TY  - JOUR
TI  - Physics basis for the reference flat-top plasma scenario in the ST–E1 fusion power plant
AU  - Steven McNamara
AU  - S. Abouelazayem
AU  - А. И. Алиева
AU  - Michail Savvas Anastopoulos Tzanis
AU  - J.W. Berkery
AU  - A. Yu. Dnestrovskij
AU  - A V Dudkovskaia
AU  - Filip Janky
AU  - Jisung Kang
AU  - Nicolas Lopez
AU  - E.N.J. Maartensson
AU  - Rajesh Maingi
AU  - Chris Marsden
AU  - Sergei Yu. Medvedev
AU  - Andrew Oakleigh Nelson
AU  - Vadim Nemytov
AU  - J. F. Parisi
AU  - Y. Ren
AU  - Matthew Robinson
AU  - M. Romanelli
AU  - A. Scarabosio
AU  - Mattia Scarpari
AU  - A. D. Sladkomedova
AU  - Timothy Stoltzfus-Dueck
AU  - Yuichi TAKASE
AU  - J. Varje
AU  - E. O. Vekshina
AU  - C. Wilson
AU  - X. Zhang
AU  - C. F. B. Zimmermann
PY  - 2026
DA  - 2026/07/10
JO  - Nuclear Fusion
DO  - 10.1088/1741-4326/ae5f33
UR  - https://doi.org/10.1088/1741-4326/ae5f33
AB  - As part of the U.S. Department of Energy’s Milestone-Based Fusion Energy Development Program, Tokamak Energy has completed the pre-concept design of the ST–E1 fusion power plant. ST–E1 is envisaged to operate in two phases: a pilot plant phase, targeting sustained net power production of 300 − 500 MWe for a duration > 1 hr , followed by a commercial power plant phase targeting steady-state operations and a normalised overnight capital cost of ⩽ 12 000 $ / kWe . The design process adopted was highly iterative, integrating all major plant systems and progressing in a phased fidelity approach. At the pre-conceptual stage, the emphasis has been on exploring the design space, identifying the main system-level trade-offs, and making the key decisions that define the overall plant concept, rather than optimising a single operating point. This paper, part of a focused collection detailing the ST–E1 pre-concept design, addresses the development of a series of reference flat-top plasma operating points for the pilot plant phase. A modelling workflow was established to develop and assess candidate plasma design points and explore key dependencies. The workflow includes integrated core plasma modelling, magnetohydrodynamic (MHD) stability assessment, equilibrium generation, scrape-off-layer and exhaust modelling, heating & current drive design and optimisation, and turbulent transport modelling. Using this framework, the impact of several key parameters on the flat-top operating space was investigated, including the density limit, core radiation fraction and divertor power loading, level of external heating and curent drive power and assumed pedestal characteristics. The MHD stability, controllability and micro-stability characteristics of these plasmas were also analysed. These investigations informed the definition of a set of fully non-inductive, flat-top reference operating points that satisfy the high-level ST–E1 mission, including a low and high density case, a case that is stable to resistive wall modes and a case with reduced divertor power loading.
SN  - 0029-5515
SN  - 1741-4326
ER  -