Towards In-situ Thermo-mechanical Property Monitoring During Ion Irradiation

Cody Dennett, Massachusetts Institute of Technology

Currently, few methods exist for characterizing irradiated material performance in situ as irradiations (neutron or ion) are taking place. The ability to continuously monitor thermal and mechanical material properties would be extremely advantageous for collecting high-dose resolution property data as well as detecting emergent irradiation-induced material responses. Transient grating spectroscopy (TGS), a surface photoacoustic technique, is a non-contact, non-destructive methodology being developed for this purpose. By optically inducing and monitoring monochromatic surface acoustic waves (SAWs) with micron-scale wavelengths, the thermal diffusivity and elastic properties of samples under interrogation can be determined. A time-resolved implementation of this methodology has been developed that has sufficient sensitivity in measured properties and the time resolution to continuously monitor microstructural evolution in materials being irradiated. Ion irradiation-induced property changes have been measured post-irradiation on pure, single crystal copper as proof-of-principle experiments. These initial studies motivate the development of an in situ TGS beamline experiment for concurrent ion beam irradiation and property monitoring. Such a facility would allow for breakaway phenomena, like volumetric void swelling, to be studied in much greater detail than is possible at present.

Abstract Author(s): Cody A. Dennett, Michael P. Short