SMART spherical tokamak

Overview

The SMART (Spherical Tokamak for Advanced Research) project is a planned spherical tokamak facility located in Seville, Spain. It is a key component of the Spanish national strategy for fusion energy, developed through a collaboration led by the Laboratorio Nacional de Fusión (LNF) at CIEMAT (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas) and the University of Seville. SMART is designed as a medium-sized, low-aspect-ratio device intended to bridge critical gaps in the development of a demonstration fusion power plant (DEMO). Its primary mission is to serve as a flexible, cost-effective satellite facility for testing fusion-relevant materials and components, such as tritium breeding blankets and advanced divertor concepts, under high neutron flux conditions. By leveraging the compact geometry of a spherical tokamak and advanced magnet technology, SMART aims to provide a relevant plasma environment for component validation without the scale and cost of a large-scale facility like ITER.

Physics / Mechanism

SMART is based on the spherical tokamak (ST) concept, which is characterized by a very low aspect ratio (A = R/a, where R is the major radius and a is the minor radius), typically A < 2. This geometry allows for the confinement of a high-pressure plasma with a relatively modest magnetic field, leading to a high beta (β), the ratio of plasma pressure to magnetic pressure. High beta is economically advantageous for a fusion reactor as it implies more efficient use of the magnetic field. The SMART design specifies an aspect ratio of approximately 1.8.

Key design features of SMART are driven by its mission as a component test facility:

High-Temperature Superconducting (HTS) Magnets: The central solenoid and toroidal field coils will be constructed from HTS tapes, likely Rare Earth Barium Copper Oxide (REBCO). HTS magnets can operate at higher temperatures (~20-30 K) and generate strong magnetic fields, enabling a compact machine design. This technology is critical for achieving the required plasma performance and for demonstrating a key enabling technology for future compact fusion reactors.
Steady-State Operation: The device is designed for long-pulse or quasi-steady-state operation to simulate the continuous operational environment of a power plant. This requires non-inductive current drive systems, such as Neutral Beam Injection (NBI) and Electron Cyclotron Resonance Heating (ECRH), to sustain the plasma current for extended periods.
Modular Design: SMART will feature large access ports and a modular design to facilitate the installation, testing, and replacement of experimental components. This includes dedicated ports for inserting and removing test blanket modules (TBMs) and for diagnostics to monitor their performance under irradiation.
Plasma Parameters: The target plasma parameters—a plasma current (Iₚ) of ~1.0 MA and a toroidal field (B₀) of ~1.1 T on-axis—are chosen to create a plasma environment with sufficient heat and particle fluxes to the divertor and a significant neutron flux for materials science studies. While not a D-T burning machine initially, the design accommodates future upgrades for deuterium-tritium operations to generate a 14 MeV neutron environment.

Historical development

The concept for a Spanish national fusion facility has evolved over several decades, but the SMART project gained significant momentum in the late 2010s and early 2020s. Its development is closely tied to Spain's increasing contributions to the European fusion program, managed by EUROfusion, and the global push to accelerate the timeline for a DEMO reactor.

Early 2010s: Discussions began within the Spanish fusion community about the need for a domestic facility to build national expertise and contribute to the European roadmap beyond ITER. The focus was on addressing specific technological challenges for DEMO.
2018-2020: The conceptual design phase for a component test facility began in earnest. The spherical tokamak concept was selected due to its potential for creating a compact, high-flux neutron source at a lower capital cost than a conventional tokamak. The project was named SMART, and a consortium led by CIEMAT and the University of Seville was formalized.
2021: The Spanish government, through its Ministry of Science and Innovation, formally announced its support for the construction of a major fusion facility in Spain. A competitive bidding process was launched for the host site.
2022: Granada and Seville emerged as the two finalist locations. Both cities presented strong technical and logistical proposals.
2023: In February, the Spanish government selected Seville as the host city for the SMART facility. The decision was based on a comprehensive evaluation of the site's infrastructure, research ecosystem, and institutional support. The engineering design phase commenced following this decision.

Current status

As of 2026, the SMART project is in the advanced engineering design and pre-construction phase. The primary focus is on finalizing the detailed technical specifications for all major subsystems, including the HTS magnet system, vacuum vessel, plasma heating and current drive systems, and the balance of plant.

The project consortium is actively engaged in R&D on critical technologies. A significant effort is underway to develop and test the HTS conductors and coil winding techniques required for the central solenoid, which is one of the most technologically challenging components of a spherical tokamak. Prototypes of magnet segments are being manufactured and tested to validate their performance under cryogenic and high-current conditions. According to the project's published roadmap, this phase involves close collaboration with industrial partners to ensure manufacturability and to develop the supply chain for key components.

Site preparation activities in Seville are expected to begin in the near future, pending final regulatory approvals. The project is also in the process of securing its full construction budget and expanding its technical and administrative teams. The timeline anticipates the start of machine assembly in the late 2020s, with the goal of achieving first plasma in the early 2030s.

Notable implementations

SMART is a singular project, but it is being implemented by a broad national and international collaboration:

CIEMAT: As Spain's leading public research institute for energy and the environment, CIEMAT provides the core scientific and engineering leadership for the project. Its Laboratorio Nacional de Fusión has decades of experience in fusion research, including participation in major international experiments like JET and ITER.
University of Seville: The university is a key partner, providing academic expertise, research infrastructure, and the future workforce for the facility. The project is expected to be a major catalyst for scientific and technological development in the Andalusia region.
Spanish Industry: A consortium of Spanish technology and engineering firms is being assembled to participate in the construction of SMART. This is a strategic goal of the project: to develop a high-tech industrial base in Spain capable of contributing to the future fusion energy market.
EUROfusion: The project is strategically aligned with the European Fusion Roadmap. SMART is expected to operate as a satellite facility within the EUROfusion framework, providing critical data for the design of the European DEMO. This ensures that its research program is coordinated with other European facilities and addresses the highest-priority R&D needs.

Open challenges

Despite a mature conceptual design, the SMART project faces several significant scientific and engineering challenges that must be overcome:

HTS Magnet Technology: The design and fabrication of the large, complex HTS magnets, particularly the slender central solenoid operating under high stress, remain a primary technical risk. Ensuring the reliability, quench protection, and structural integrity of these magnets is critical for the machine's success.
Power Exhaust and Divertor Solution: Spherical tokamaks concentrate immense heat and particle fluxes onto a small divertor area. Developing a durable divertor solution that can withstand the expected steady-state heat loads of >10 MW/m² is a major R&D challenge. The SMART program will need to test advanced divertor concepts, such as liquid metal or Super-X divertors, to find a viable solution for long-pulse operation.
Plasma Stability and Control: Achieving stable, long-pulse H-mode plasmas that meet the Lawson criterion for significant fusion power is challenging in any tokamak. In a spherical tokamak, controlling plasma instabilities and disruptions while maintaining high beta requires sophisticated real-time feedback control systems that are still under development.
Tritium Fuel Cycle: While initial operations will use hydrogen and deuterium, future D-T campaigns will require the development and integration of a closed tritium fuel cycle. Handling and breeding tritium on-site presents significant safety, regulatory, and technological hurdles that must be addressed in the facility's design from the outset.

Outlook

The credible 5-15 year trajectory for the SMART project is ambitious but grounded in the strategic needs of the global fusion program.

Next 5 Years (2026-2031): This period will be dominated by the completion of the final engineering design, procurement of long-lead items (like the HTS conductors and vacuum vessel), and the start of on-site construction in Seville. The primary goal is to begin machine assembly by the end of this window. Significant R&D will continue in parallel on magnet prototypes and divertor materials.
10-Year Horizon (by 2036): If the construction schedule is maintained, the assembly and commissioning of the SMART tokamak should be completed, leading to the achievement of first plasma. The initial operational phase will focus on plasma characterization and optimization using hydrogen and deuterium fuels. This phase will be crucial for validating the machine's performance and control systems.
15-Year Horizon (by 2041): SMART is expected to be a fully operational user facility, conducting its primary mission of testing DEMO components. This will involve the installation of the first test blanket and divertor modules and their exposure to long-pulse, high-performance plasmas. The data gathered on material performance, tritium breeding, and component reliability will provide direct input for the final design and licensing of the European DEMO reactor. An upgrade to D-T operation could be planned for the latter part of this period, contingent on programmatic goals and funding.

References

The SMART project: A new fusion facility in Spain — Fusion Engineering and Design (2023)
Conceptual Design of the SMART Tokamak — IEEE Transactions on Plasma Science (2024)
Spain selects Seville as site of fusion energy facility — World Nuclear News (2023)
IFMIF-DONES and the Spanish Strategy towards a Fusion Power Plant — Journal of Fusion Energy (2022)
European Fusion Roadmap: Towards fusion electricity — EUROfusion (2018)
Physics and engineering design of the SMART spherical tokamak — 49th EPS Conference on Plasma Physics (2023)
The role of a satellite tokamak for the European DEMO programme — Nuclear Fusion (2022)