Thermal diffusivity variation assessment on Radio-Frequency Quadrupole Cu-OF copper due to proton irradiation

Particle accelerator components are exposed to high radiation environments that could lead to material property degradation and affect component’s performance and lifetime. The ability to deploy rapid, multi-modal, non-destructive techniques provides valuable insight in microstructure evolution of radiation induced effects. The current work demonstrates the use of Transient Grating Spectroscopy (TGS) as a powerful technique to detect post irradiation changes in thermal diffusivity of polycrystal, high-purity, oxygen-free copper (Cu-OF) used in Radio-Frequency Quadrupoles (RFQs). For that purpose, the nominal operation proton beam losses of the European Spallation source (ESS) RFQ were studied to define copper sample irradiation patterns at MIT Tandetron accelerator that emulate the radiation damage conditions corresponding to 24 h of operation. Sample measurements with TGS before and after irradiation were performed in order to assess potential variation in copper thermal properties. Irradiated samples with energy of 120 keV, incident angles of 0°, 40° and fluence of 1017 p/cm2 at room temperature and resulted damage of 0.015 dpa presented a decrease in their thermal diffusivity which can be attributed to point defect generation and void formation.