Tokamak Energy’s pre-concept design for a fusion power plant: an overview of ST-E1

Willis, Johannes [Tokamak Energy Ltd., Oxford (United Kingdom)]; McNamara, S. A. M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000204775247); Maartensson, E. N. J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000072898516); Astbury, J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:000900026198638X); Yildirim, E. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000219031857); Hinton, N. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000646934054); Wilson, C. L. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000788603867); Zhang, X. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000337755821); Berkery, J. W. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000280623210); Baylor, L. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000203257771); Shimada, M. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:000000021592843X); Flynn, H. [Savannah River National Laboratory (SRNL), Aiken, SC (United States)]; Nelson, A. O. [Columbia Univ., New York, NY (United States)] (ORCID:0000000296121936); Abouelazayem, S. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000062919854); Alieva, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000245734951); Anderson, T. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Benayas, J. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Black, L. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000512090220); Borscz, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000287358376); Bristow, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000290227078); Brown, S. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Bunting, P. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000264930632); Burchill, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000329108867); Chandrasekhar, K. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000589573060); Cheema, P. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Danisworo, O. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Dnestrovskii, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000248279421); Dudkovskaia, A. V. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000168903079); England, J. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Fowler, J. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Godhani, V. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000103086298); Guise, E. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Irukuvarghula, S. [Tokamak Energy Ltd., Oxford (United Kingdom)]; James, D. [Tokamak Energy Inc., Washington, DC (United States)]; Janky, F. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000194887188); Kamal, G. S. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000097114941); Kang, J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000298454646); Kruip, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000727222649); Kumar, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000260265727); Lee, V. Y. S. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000252397762); Levine, S. M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:000000029562104X); Lima, J. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Lopez, N. A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000155663731); Loughran, I. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Malinowski, F. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000161174202); Marsden, C. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000313225236); Mateescu, L. [Tokamak Energy Ltd., Oxford (United Kingdom)]; McAdam, A. F. P. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000939043183); Medvedev, S. Y. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000293589402); Michalopoulou, M. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Mohamed, M. K. E. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000888920827); Naish, J. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Naylor, G. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000902794506); O’Dea, D. [Tokamak Energy Inc., Washington, DC (United States)] (ORCID:0000000224463232); Pickles, J. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Pocock, R. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Robinson, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000307091219); Romanelli, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000348974843); Romanelli, S. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Scarabosio, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000273726975); Scarpari, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000162460131); Scott, A. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Shone, A. [Tokamak Energy Inc., Washington, DC (United States)] (ORCID:0000000199371124); Sladkomedova, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000200129328); Soldatova, A. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Srawley, T. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Stirling, J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000291236379); Stoneham, G. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Suhardjo, R. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Takase, Y. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000248465267); Taylor, J. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Terry, S. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Thwaites, R. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Trueba, J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000762599281); van Nugteren, B. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Varje, J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000341372436); Vekshina, E. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000197715579); Vincent, B. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:000900095293444X); Vorobev, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000264589390); Washington II, A. L. [Tokamak Energy Inc., Washington, DC (United States)] (ORCID:0000000237205160); Welch, N. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000228524207); Whitehead, A. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Whitfield, M. [Tokamak Energy Ltd., Oxford (United Kingdom)]; Wooldridge, E. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000670422569); Ginsberg, M. [Tokamak Energy Inc., Washington, DC (United States)] (ORCID:0000000304237032)

doi:10.1088/1741-4326/ae5545

DOE OSTI · 3378206

Tokamak Energy’s pre-concept design for a fusion power plant: an overview of ST-E1

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Abstract

Climate change and rapidly rising energy demand, driven in part by artificial intelligence and data-centre growth, create an urgent need for stable, low-carbon, and abundant power. Fusion is a promising long-term solution, yet its commercialisation faces a fundamental paradox in today’s investment environment: pilot plants are essential to de-risk physics, engineering, and operations, but their limited lifetime energy output and high upfront costs make them difficult to finance. This paper presents Tokamak Energy’s response: ST-E1, a pre-concept design for a low-aspect-ratio tokamak power plant engineered specifically to overcome this challenge. ST-E1 is designed from the outset for phased operation—pilot and commercial phases, with an upgrade phase in between—with emphasis on commercial viability, maintainability, nuclear engineering, modularity, and upgradability. A key design principle is the deliberate separation of long-lived assets, such as the magnet cage and vacuum vessel, from replaceable in-vessel systems. This provides an attractive and credible investment approach to generate operational data and de-risk key technologies while preserving most capital-intensive assets for later commercial phases. The architecture supports continuous optimisation toward high net electric power (targeting 800–1000 MW net electric), a normalised capital expenditure of $\$$ 12–14k/kW of net electric power, and high availability (targeting > 80%). A tokamak core with a 5 m major radius, aspect ratio of 2.3, and on-plasma axis toroidal field of 5.25 T was selected to meet these objectives. This paper summarises the ST-E1 design philosophy, principal features, and development methodology. It introduces a Focus Collection of 11 papers detailing the pre-concept design of the entire tokamak and corresponding plant.

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Willis, Johannes [Tokamak Energy Ltd., Oxford (United Kingdom)], McNamara, S. A. M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000204775247), Maartensson, E. N. J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000072898516), Astbury, J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:000900026198638X), Yildirim, E. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000219031857), Hinton, N. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000646934054), Wilson, C. L. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000788603867), Zhang, X. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000337755821), Berkery, J. W. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)] (ORCID:0000000280623210), Baylor, L. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000203257771), Shimada, M. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)] (ORCID:000000021592843X), Flynn, H. [Savannah River National Laboratory (SRNL), Aiken, SC (United States)], Nelson, A. O. [Columbia Univ., New York, NY (United States)] (ORCID:0000000296121936), Abouelazayem, S. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000062919854), Alieva, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000245734951), Anderson, T. [Tokamak Energy Ltd., Oxford (United Kingdom)], Benayas, J. [Tokamak Energy Ltd., Oxford (United Kingdom)], Black, L. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000512090220), Borscz, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000287358376), Bristow, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000290227078), Brown, S. [Tokamak Energy Ltd., Oxford (United Kingdom)], Bunting, P. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000264930632), Burchill, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000329108867), Chandrasekhar, K. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000589573060), Cheema, P. [Tokamak Energy Ltd., Oxford (United Kingdom)], Danisworo, O. [Tokamak Energy Ltd., Oxford (United Kingdom)], Dnestrovskii, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000248279421), Dudkovskaia, A. V. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000168903079), England, J. [Tokamak Energy Ltd., Oxford (United Kingdom)], Fowler, J. [Tokamak Energy Ltd., Oxford (United Kingdom)], Godhani, V. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000103086298), Guise, E. [Tokamak Energy Ltd., Oxford (United Kingdom)], Irukuvarghula, S. [Tokamak Energy Ltd., Oxford (United Kingdom)], James, D. [Tokamak Energy Inc., Washington, DC (United States)], Janky, F. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000194887188), Kamal, G. S. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000097114941), Kang, J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000298454646), Kruip, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000727222649), Kumar, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000260265727), Lee, V. Y. S. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000252397762), Levine, S. M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:000000029562104X), Lima, J. [Tokamak Energy Ltd., Oxford (United Kingdom)], Lopez, N. A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000155663731), Loughran, I. [Tokamak Energy Ltd., Oxford (United Kingdom)], Malinowski, F. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000161174202), Marsden, C. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000313225236), Mateescu, L. [Tokamak Energy Ltd., Oxford (United Kingdom)], McAdam, A. F. P. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000939043183), Medvedev, S. Y. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000293589402), Michalopoulou, M. [Tokamak Energy Ltd., Oxford (United Kingdom)], Mohamed, M. K. E. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000888920827), Naish, J. [Tokamak Energy Ltd., Oxford (United Kingdom)], Naylor, G. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000902794506), O’Dea, D. [Tokamak Energy Inc., Washington, DC (United States)] (ORCID:0000000224463232), Pickles, J. [Tokamak Energy Ltd., Oxford (United Kingdom)], Pocock, R. [Tokamak Energy Ltd., Oxford (United Kingdom)], Robinson, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000307091219), Romanelli, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000348974843), Romanelli, S. [Tokamak Energy Ltd., Oxford (United Kingdom)], Scarabosio, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000273726975), Scarpari, M. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000162460131), Scott, A. [Tokamak Energy Ltd., Oxford (United Kingdom)], Shone, A. [Tokamak Energy Inc., Washington, DC (United States)] (ORCID:0000000199371124), Sladkomedova, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000200129328), Soldatova, A. [Tokamak Energy Ltd., Oxford (United Kingdom)], Srawley, T. [Tokamak Energy Ltd., Oxford (United Kingdom)], Stirling, J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000291236379), Stoneham, G. [Tokamak Energy Ltd., Oxford (United Kingdom)], Suhardjo, R. [Tokamak Energy Ltd., Oxford (United Kingdom)], Takase, Y. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000248465267), Taylor, J. [Tokamak Energy Ltd., Oxford (United Kingdom)], Terry, S. [Tokamak Energy Ltd., Oxford (United Kingdom)], Thwaites, R. [Tokamak Energy Ltd., Oxford (United Kingdom)], Trueba, J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000762599281), van Nugteren, B. [Tokamak Energy Ltd., Oxford (United Kingdom)], Varje, J. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000341372436), Vekshina, E. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000197715579), Vincent, B. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:000900095293444X), Vorobev, A. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000264589390), Washington II, A. L. [Tokamak Energy Inc., Washington, DC (United States)] (ORCID:0000000237205160), Welch, N. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0000000228524207), Whitehead, A. [Tokamak Energy Ltd., Oxford (United Kingdom)], Whitfield, M. [Tokamak Energy Ltd., Oxford (United Kingdom)], Wooldridge, E. [Tokamak Energy Ltd., Oxford (United Kingdom)] (ORCID:0009000670422569), Ginsberg, M. [Tokamak Energy Inc., Washington, DC (United States)] (ORCID:0000000304237032). 2026-07-10. Tokamak Energy’s pre-concept design for a fusion power plant: an overview of ST-E1. https://doi.org/10.1088/1741-4326/ae5545

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