Commercial fusion power plants demand magnet materials that retain structural integrity and thermal conductivity while operating under neutron bombardment at cryogenic temperatures. Understanding how thermo-mechanical properties evolve under these conditions is crucial for selecting materials with high radiation tolerance and predictable failure mechanisms. Presented here is a facility that combines cryogenic transient grating spectroscopy with simultaneous ion irradiation, enabling in situ measurements of thermal diffusivity and surface acoustic wave (SAW) frequencies, allowing inference of microstructural evolution. Using copper as a benchmark material, an irradiation was performed at 30 K with 12.4 MeV ions producing a fluence of ions m−2. Over the irradiation period, thermal diffusivity nearly halved from an initial value of while SAW speed did not show significant changes, maintaining a value of m s−1. Given its real-time monitoring capability and the numerous candidate materials that remain under characterized under fusion magnet operating conditions, this facility is poised to deliver new scientific insights into fusion magnet material degradation trends, contributing to improved design criteria and operational certainty for forthcoming fusion power plants.
This paper presents a facility that can measure the thermal and mechanical properties of materials used in fusion reactor magnets under cryogenic temperatures and ion irradiation. The results show that the thermal diffusivity of copper decreases significantly during irradiation, while the surface acoustic wave speed remains stable. This facility can provide valuable insights into how fusion magnet materials degrade under operating conditions, which is crucial for designing reliable and efficient fusion power plants.