Speaker
Description
A repository storing key performance data collected from integrated material testing on the DIII-D tokamak is being actively developed in collaboration with the Clean Air Task Force Material Database for Fusion (MatDB4Fusion) initiative to aid in material down-selection for commercial fusion reactor deployment. Advancing the technological readiness level of plasma-facing materials (PFMs) requires combined effect testing to assess synergies that may impact survivability. The Divertor Material Evaluation System (DiMES) [1,2] is a material testing platform installed in the lower divertor of the DIII-D tokamak with world-leading diagnostic coverage. Coupon-sized (⌀ 0.6-2.5 cm) samples of varying compositions and geometries are loaded into DiMES, exposed to reactor-relevant heat and particle fluxes, and characterized using a comprehensive suite of spectroscopy and plasma diagnostics. Three decades investigating different materials across a wide range of plasma scenarios has produced one of the largest sources of combined effect data that is now being synthesized and made accessible to the PMI community via MatDB4Fusion.
The DiMES material database provides key performance metrics for several reactor-relevant PFMs exposed to combined effect loading across a range of plasma conditions. Gross and net erosion rates are based on in situ emission spectroscopy and post-mortem Rutherford Backscattering Spectroscopy measurements. Thermal handling is quantified via embedded thermocouples and infrared (IR) camera temperature measurements and is linked qualitatively to changes in surface morphology (e.g., recrystallization, melting) quantified ex situ before and after exposure via microscopy. Fuel retention is quantified by post-mortem nuclear reaction analysis and thermal desorption spectroscopy. Edge-localized mode (ELM)-resolved measurements of local plasma conditions (e.g., electron temperature, particle flux, and heat flux) using Langmuir probes, Thomson scattering, spectroscopy, and IR imaging link the material response to loading conditions, offering insight on the underlying physics processes at the plasma-material interface.
Constructing a comprehensive material property database will reduce risk and stimulate growth in fusion reactor design. Characterization of changes during combined effect loading provides actionable insight on performance once in operation. Valuable data from integrated plasma exposure testing performed on the DiMES testing platform has now been compiled and coupled to MatDB4Fusion to support the growing commercial fusion industry. Curating high-quality datasets with a standardized protocol will enable machine learning tools to detect performance trends, predict material behavior, and accelerate design cycles for next-generation PFMs.
[1] Wong C.P.C. et al 1998 J. Nucl. Mater. 258–263 433-439
[2] Rudakov D.L. et al 2017 Fusion Eng. Des. 124 196-201