Project objectives
The SF-Plant project aims to evaluate the extent to which high-temperature superconductors (HTS) enable the construction of fusion power plants that are more compact and attractive than those using low-temperature superconductors. The goal is to explore a wide range of parameters and technological solutions in order to identify candidate designs for future power plants.
Scientific background
Magnetic confinement fusion relies on the creation and maintenance of a hot plasma confined by a magnetic field. HTSs offer a unique opportunity to intensify this field, which improves plasma confinement and makes smaller, less expensive power plants feasible.
However, while this approach is promising, it presents certain challenges. In particular, the higher magnetic field generates extreme Laplace forces on the coils and intensifies the heat fluxes deposited locally by the plasma on the wall.
Methodology and approach
01
System Studies
The SF-Plant project will first develop and use system codes—that is, simplified codes describing an entire magnetic fusion power plant to rapidly explore the parameter space (size, magnetic field, ...) and identify potentially interesting designs. This work will focus primarily on tokamaks, but stellarators will also be studied, and other configurations may also be considered
02
Analysis of Candidate Designs
The designs identified during the system studies will then be analyzed in greater detail using advanced simulation tools. These tools will enable more accurate modeling of the power plant’s various components including the coils, the plasma, and the first-wall components in order to evaluate their performance and feasibility.
03
Upstream Studies
Finally, alongside these activities, an “upstream” component will be developed to understand certain key physical aspects (for example, those related to heat fluxes deposited by the plasma on the wall) or to investigate innovative technologies capable of addressing the challenges associated with HTSs (for example, liquid metal wall components that are more resilient to heat fluxes).
Scientific and technological challenges
Laplace forces
Manage the intense forces on coils induced by high magnetic fields.
Heat Flow
Manage heat transfer in components exposed to plasma, which can be particularly intense in the presence of a strong magnetic field.
Design of Compact Fusion Power Plants
Identify, study, and optimize—using simulation codes—the design of compact fusion power plants based on various confinement concepts (tokamak, stellarator, etc.).
Upstream Studies
To improve our understanding and models and to explore innovative technologies regarding key aspects related to HTS-based fusion machines.
Partners involved
This project is being carried out in collaboration with several laboratories and research centers
CEA
Project leader, responsible for systems analysis, cryomagnetic system design, tritium blanket design, and plasma modeling (scenarios, MHD stability, heating)
CNRS
In charge of research on stellarators and other configurations, development of wall components using liquid metals, and modeling of the core plasma (turbulent transport)
AMU
Modeling of the core plasma (turbulent transport) and the divertor plasma
CentraleSupélec
Technical and Economic Analysis and Optimization of Electrical Systems Based on HTSs
UCA
Design of the Poloidal Magnetic Field System
DVHE
Modeling of core plasma (turbulent transport)
Notable Results
Scientific kickoff meeting held at CEA Cadarache (IRFM) from March 24 to 26, 2025. Annual workshop held in Aix-en-Provence from May 4 to 7, 2026.
Group photo from the annual SF-Plant workshop held in Aix-en-Provence from May 4 to 7, 2026
Development of the D0FUS system code and application to assess the impact of HTSs on the design of DEMO-type tokamaks and to define a preliminary design for the “SF-Plant tokamak” (an HTS) tokamak delivering 2 GW of fusion power)
D0FUS map showing the feasibility range in terms of major radius (R0) and small radius (a) for a tokamak producing 2 GW of fusion power using HTSs, with a magnetic field of 20 T at the inner leg of the toroidal coils. The feasibility region is bounded by the solid black curve. This curve varies depending on the “levers” used (choice of mechanical architecture, type of steel used, plasma current drive, etc.), and it is plotted here to include all possible levers. The stars indicate the most compact designs possible when applying only certain subsets of the levers. [Auclair arXiv 2026] [Auclair SOFT 2026]
In artist’s renderings (using the same scale) comparing the SF-Plant tokamak (left) and EU-DEMO (right). Both tokamaks are designed to deliver 2 GW of fusion power.
Development of the CIRCE code for the mechanical analysis of the toroidal coil system and the central solenoid, and application to the preliminary design of the “SF-Plant tokamak” (an HTS) tokamak generating 2 GW of fusion power)
Left: Diagram showing the geometry used in CIRCE, which combines a thin-beam model for the toroidal coils and a sheet model for the inter-coil structures. Right: Distribution of Tresca stress in a “Princeton D”-type coil for the SF-Plant tokamak. [Boudes IEEE 2026] [Boudes SOFT 2026]