SIBAF Project Secures €9.7 Million for Fusion Materials and Accelerator Research

A new €9.7 million research project at Germany’s GSI Helmholtzzentrum für Schwerionenforschung and the FAIR accelerator center is set to transform how materials for future fusion power plants are tested. Known as SIBAF, an acronym derived from the German title “Supraleitender Ionenbeschleuniger als BAsistechnologie für die Fusionsforschung,” the three-year initiative will create an accelerator-based infrastructure for rapidly qualifying materials exposed to extreme radiation. The Federal Ministry of Research, Technology and Space will provide the funding through its “Basic Technologies for Fusion—On the Way to a Fusion Power Plant” program. Of the total award, €8.1 million will support activities at GSI and FAIR, while Goethe University Frankfurt will participate as the project’s academic partner. The effort links superconducting accelerator engineering with nuclear materials science, targeting one of fusion energy’s most stubborn technical barriers: finding substances that can survive inside a reactor for years.

Fusion promises an abundant source of low-carbon energy by combining light atomic nuclei under conditions hotter than the center of the Sun. On Earth, however, the same reactions generate an exceptionally hostile environment for the structures surrounding the plasma. Future fusion reactors will expose walls, blankets, supports and other components to intense heat, energetic particles and a persistent flux of high-energy neutrons. Those neutrons can displace atoms from their normal positions in a crystal lattice, creating vacancies, interstitial defects, dislocation networks and, in some materials, helium-filled bubbles. Over time, these microscopic changes can cause swelling, embrittlement, loss of thermal conductivity and reduced mechanical strength. A material that performs well in a conventional laboratory furnace may therefore fail under fusion conditions. The ability to reproduce and measure such damage efficiently is essential before any reactor component can be trusted during long periods of operation.

Neutron irradiation experiments remain the most direct way to study the damage expected in a fusion environment, but they are difficult to perform at the speed required by modern materials development. Suitable neutron sources are scarce, experiments can be expensive and samples may become activated, meaning they continue to emit radiation after irradiation. Handling, transporting and analyzing those samples can require specialized facilities and strict safety procedures. Heavy-ion irradiation offers a complementary route. In this approach, beams of energetic ions are directed into a material, transferring momentum to atoms and generating collision cascades that resemble important aspects of neutron-induced damage. Because ion beams can deliver damage rapidly and under tightly controlled conditions, researchers can compare candidate alloys, ceramics and engineered materials in much shorter experimental cycles. The method does not replace neutron testing, but it can help researchers identify the most promising materials before committing them to slower and more costly qualification programs.

SIBAF will build its new capability around HELIAC, the Helmholtz Linear Accelerator, a superconducting continuous-wave accelerator being developed on the GSI/FAIR campus. Unlike pulsed machines, a continuous-wave accelerator is designed to deliver a nearly uninterrupted beam, allowing experiments to receive a stable stream of ions over extended periods. The project will use HELIAC’s first cryomodule together with the existing high-charge-state injector, or HLI, at GSI and FAIR. The injector prepares ions by removing many of their electrons, producing highly charged particles that can be accelerated efficiently. Superconducting radio-frequency cavities then transfer energy to the beam while operating at cryogenic temperatures, where electrical resistance is extremely low. This architecture is intended to provide a powerful, energy-efficient and precisely controllable ion source for materials research rather than relying solely on accelerator configurations designed for nuclear-physics experiments.

The planned irradiation facility will be engineered for more than simply directing ions at a target. SIBAF will introduce temperature-controlled sample environments so that researchers can examine how radiation damage develops at conditions relevant to future reactor components. Temperature strongly influences defect mobility: vacancies and interstitials may recombine, migrate to grain boundaries or cluster into larger structures depending on how hot the material becomes. By controlling temperature during irradiation, scientists can study damage accumulation under different operating scenarios and distinguish short-lived defects from changes that permanently alter a material’s microstructure. Automated sample handling will further increase the number of experiments that can be conducted while improving reproducibility. Robotic or computer-controlled procedures can position samples, adjust exposure conditions and move specimens between stages with less variability than manual handling, creating more reliable datasets for comparison.

The resulting infrastructure could accelerate a crucial feedback loop in fusion materials research. Researchers may irradiate several candidate materials, characterize their microscopic and macroscopic changes, refine their compositions or manufacturing methods, and then test improved versions in a new cycle. Advanced characterization can reveal how irradiation modifies grain structures, phase distributions, surface morphology, hardness, strength and thermal behavior. These results can be connected to computational models that predict how defects form and evolve over time. Heavy-ion experiments are particularly valuable when a research team needs controlled comparisons, such as exposing different alloys to the same ion species, energy, temperature and dose. The facility’s continuous-wave beam is expected to support faster and more uniform damage accumulation, potentially reducing the energy required per useful experiment while increasing the precision of measurements.

For GSI and FAIR, the project also represents an application of accelerator technology beyond the traditional study of atomic nuclei and fundamental particles. Dr. Maksym Miski-Oglu, who leads the cw-Linac working group and coordinates SIBAF, said the initiative will transfer years of expertise in superconducting linear accelerators into a practical fusion application. Professor Maria Eugenia Toimil-Molares, head of Materials Research, described the HELIAC-based facility as a complement to the existing ion-beam infrastructure at GSI and FAIR. Together, the facilities could provide researchers with a broader toolkit for studying radiation effects and designing materials for extreme environments. The approach is significant because no single irradiation method perfectly reproduces every condition inside a fusion reactor. Combining different beam technologies, temperatures, analysis methods and eventually neutron experiments can provide a more complete picture of how a material will behave.

The program is also intended to strengthen the human infrastructure behind fusion technology. Professor Thomas Nilsson, Scientific Managing Director of GSI and FAIR, said the funding recognizes the importance of accelerator science and materials research to future energy systems. SIBAF is expected to train scientists and engineers in two fields that must work closely together: the design and operation of high-performance ion accelerators, and the development of materials capable of surviving radiation. That combination could be especially important as fusion research moves from plasma demonstrations toward integrated power-plant concepts. A successful reactor will require not only a plasma that produces more energy than is used to sustain it, but also walls, blankets, magnets, cooling systems and structural components that can operate safely and economically. The consortium has also acknowledged Professor Winfried Barth for his contribution to conceiving and preparing the project proposal.

SIBAF forms part of Germany’s broader “Fusion 2040—Research on the Way to the Fusion Power Plant” strategy, which aims to establish the scientific and technological foundations for constructing and operating a future fusion plant. Its immediate goal is not to generate fusion electricity, but to solve a problem that could determine whether fusion power becomes commercially practical: how to qualify materials quickly enough, accurately enough and at a realistic cost. By combining HELIAC’s superconducting continuous-wave beam, GSI and FAIR’s high-charge-state injector, automated irradiation systems and controlled thermal environments, the project will create a specialized European platform for that task. If the infrastructure performs as planned, it could help researchers eliminate weak material candidates earlier, optimize promising ones faster and supply the evidence needed to design components for reactors built to withstand years of intense neutron and heat exposure.