New research consortium tests materials for fusion power plants

Materials for future fusion power plants are to be developed at the Garching Research Campus. As part of a new federal programme, several research groups are pooling their expertise.

The German Federal Ministry of Research, Technology and Space (BMFTR) is funding the three-year FUMA project with around €4.8 million under its High-Tech Agenda Germany. The project partners are the Heinz Maier-Leibnitz Research Neutron Source (FRM II), the Technical University of Munich (TUM) and the Max Planck Institute for Plasma Physics (IPP).  

Inside a fusion reactor, materials are simultaneously exposed to extreme temperatures, mechanical stresses and intense particle radiation. These conditions alter the crystal lattice, create defects and pores, and can ultimately lead to material failure. The materials affected include ferritic steels such as EUROFER97, tungsten and tungsten alloys for the inner reactor wall, as well as copper alloys for cooling components. Neutron irradiation also causes rhenium to form in tungsten, altering the material’s properties.

This is where FUMA comes in. Its full German title translates as “From the atom to the plasma-facing wall: Centre of expertise for the optimisation of fusion materials”. The project brings together one positron and three neutron research groups from FRM II, along with two IPP groups whose methods complement one another. One group investigates additively manufactured components and welded joints, while another analyses pores and internal stresses under conditions close to those found in industry.

“With our positron spectroscopy at FRM II, we aim to understand material damage at the atomic level. Using the antiparticles of electrons, we can trace how the smallest defects develop into larger structures that ultimately determine the lifetime of a material,” explains project coordinator Professor Christoph Hugenschmidt of TUM.

Professor Christian Pfleiderer, Scientific Director of FRM II, adds: “The neutron-based methods used at FRM II provide unique insights into the structure of fusion materials, from the atomic scale through to the millimetre scale.”

Hugenschmidt explains why Garching offers ideal conditions for the project: “IPP contributes the highest level of local expertise in materials and components for a future fusion reactor.” The campus also offers unique experimental capabilities: heat loads of up to 20 megawatts per square metre and targeted material damage caused by neutron irradiation can be investigated under realistic conditions.

IPP is represented in the project by Professor Rudolf Neu and Professor Jeong-Ha You, both from Plasma Edge and Wall – Plasma Component Interaction, and Dr Thomas Schwarz-Selinger from Plasma Edge and Wall – Ion Beam Analysis and Modification.

The long-term goal is to be able to predict reliably the lifetime of materials inside a fusion reactor. The groups are jointly developing a measurement programme. IPP defines the research priorities for material-related questions and prepares samples, while the analysis groups at FRM II further develop their neutron and positron instruments and investigate the underlying damage mechanisms.