Integrated physics and magnet design for the ST-E1 fusion power plant
- 1Tokamak Energy Ltd
- 2Tokamak Energy Ltd, Milton Park, Oxfordshire, United Kingdom of Great Britain and Northern Ireland
Abstract
ST-E1 is Tokamak Energy’s commercially competitive fusion power plant design featuring a lifetime high-temperature superconducting (HTS) magnet cage, which has completed its pre-concept design stage. A central challenge at the pre-concept stage is the need to iteratively and consistently integrate the development of the magnet cage, core plasma physics, and power-exhaust systems, while avoiding serial design loops and late discovery of infeasible operating scenarios. Accurate representation of inductive current drive is particularly critical, as it tightly couples magnetic equilibria, flux swing, and HTS operational limits across these systems. To address this challenge, a novel integrated workflow has been developed to enable rapid, early-stage iteration during the pre-concept design phase. A key novelty is the deliberate de-coupling of magnetic equilibria generation from coil optimisation and detailed engineering, allowing a broad range of time-dependent operating scenarios to be explored without repeated high-fidelity coil redesign. The workflow combines Metis, a fast 1.5D fixed-boundary modelling tool, with FreeGS, a free-boundary equilibrium solver, to generate flat-top and time-dependent ramp-up scenarios together with the associated flux-swing traces and magnetic equilibria. These outputs are passed to SCOPE, an in-house tool that optimises poloidal field and central solenoid coils based on physics requirements while respecting HTS operational limits. The resulting coil designs are then refined within a dedicated coil-engineering workflow performing higher-fidelity structural, electromagnetic, and HTS analyses. The integrated workflow has been applied to evaluate a wide range of ramp-up, ramp-down, and flat-top scenarios, enabling consistent down-selection of technically achievable operating points across all phases of ST-E1operation. The resulting set of coils and operating scenarios collectively satisfy the full system requirements of the ST-E1 pre-concept design.
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BibTeX
@article{maartensson2026integrated,
title = {{Integrated physics and magnet design for the ST-E1 fusion power plant}},
author = {E.N.J. Maartensson and N. Welch and Mattia Scarpari and F. Malinowski and Marcus Borscz and Matthew Bristow and P.F. Buxton and Jisung Kang and M. Kruip and A.V. Langtry and Nicolas Lopez and Chris Marsden and Steven McNamara and Sergei Yu. Medvedev and Yuichi TAKASE and Paul Thomas and B. van Nugteren and C.L. Wilson and X. Zhang and the ST-E1 Team},
journal = {Nuclear Fusion},
year = {2026},
month = jul,
doi = {10.1088/1741-4326/ae773b},
url = {https://doi.org/10.1088/1741-4326/ae773b},
note = {CC BY},
}
RIS
TY - JOUR
TI - Integrated physics and magnet design for the ST-E1 fusion power plant
AU - E.N.J. Maartensson
AU - N. Welch
AU - Mattia Scarpari
AU - F. Malinowski
AU - Marcus Borscz
AU - Matthew Bristow
AU - P.F. Buxton
AU - Jisung Kang
AU - M. Kruip
AU - A.V. Langtry
AU - Nicolas Lopez
AU - Chris Marsden
AU - Steven McNamara
AU - Sergei Yu. Medvedev
AU - Yuichi TAKASE
AU - Paul Thomas
AU - B. van Nugteren
AU - C.L. Wilson
AU - X. Zhang
AU - the ST-E1 Team
PY - 2026
DA - 2026/07/10
JO - Nuclear Fusion
DO - 10.1088/1741-4326/ae773b
UR - https://doi.org/10.1088/1741-4326/ae773b
AB - ST-E1 is Tokamak Energy’s commercially competitive fusion power plant design featuring a lifetime high-temperature superconducting (HTS) magnet cage, which has completed its pre-concept design stage. A central challenge at the pre-concept stage is the need to iteratively and consistently integrate the development of the magnet cage, core plasma physics, and power-exhaust systems, while avoiding serial design loops and late discovery of infeasible operating scenarios. Accurate representation of inductive current drive is particularly critical, as it tightly couples magnetic equilibria, flux swing, and HTS operational limits across these systems. To address this challenge, a novel integrated workflow has been developed to enable rapid, early-stage iteration during the pre-concept design phase. A key novelty is the deliberate de-coupling of magnetic equilibria generation from coil optimisation and detailed engineering, allowing a broad range of time-dependent operating scenarios to be explored without repeated high-fidelity coil redesign. The workflow combines Metis, a fast 1.5D fixed-boundary modelling tool, with FreeGS, a free-boundary equilibrium solver, to generate flat-top and time-dependent ramp-up scenarios together with the associated flux-swing traces and magnetic equilibria. These outputs are passed to SCOPE, an in-house tool that optimises poloidal field and central solenoid coils based on physics requirements while respecting HTS operational limits. The resulting coil designs are then refined within a dedicated coil-engineering workflow performing higher-fidelity structural, electromagnetic, and HTS analyses. The integrated workflow has been applied to evaluate a wide range of ramp-up, ramp-down, and flat-top scenarios, enabling consistent down-selection of technically achievable operating points across all phases of ST-E1operation. The resulting set of coils and operating scenarios collectively satisfy the full system requirements of the ST-E1 pre-concept design.
SN - 0029-5515
SN - 1741-4326
ER -