Speaker: Rob Kolasinski, Sandia National Lab
Title: Evaluating the Performance of Next Generation Plasma-Facing Materials
Abstract: The study of plasma-material interactions is essential for advancing magnetic fusion as a viable energy source. Predicting how materials respond in the extreme environments typical of fusion devices presents significant technical challenges. Key aspects of this problem include understanding how materials are impacted by intense particle bombardment from D+T plasmas, as well as heat fluxes that exceed 10 MW m−2. Changes in surface composition and structure are critical, as they are closely linked to material degradation and influence recycling processes.
Our group at Sandia-Livermore focuses on experiments and modeling to better understand the effects of high-flux plasmas on materials. This presentation will highlight recent R&D on advanced tungsten alloys, which are among the best candidate plasma-facing materials for fusion devices. These materials rely on dopants or dispersoids to stabilize the microstructure and enhance their thermomechanical properties. However, significant gaps remain in our understanding of how these factors influence their response to high-flux plasma exposure.
We have characterized these performance aspects using a wide range of in-situ and post-mortem diagnostics. One class of materials we recently studied includes tungsten with small (100 nm diameter) metal-oxide and carbide-based dispersoids. Exposure to laboratory plasmas has shown promising results, indicating improved resistance to recrystallization and the formation of subsurface defects, with only a modest increase in hydrogen isotope retention. This work motivated recent experiments at the DIII-D National Fusion Facility, where we exposed several tungsten microstructures to divertor plasmas. Post-test microscopy revealed that dispersoid strengthening significantly enhanced the surface's resilience against roughening and recrystallization while also increasing its susceptibility to cracking. These tests provide guidance on material optimization and serve as a pathway toward next-generation tungsten alloys and ultra-high temperature ceramics as plasma-facing materials. Forthcoming plans to investigate these materials in greater detail will be discussed.
Bio Sketch: Rob Kolasinski is a Distinguished Member of the Technical Staff at Sandia National Laboratories in Livermore, CA. His research focuses on plasma-surface interactions, materials for hydrogen storage and hydrogen energy infrastructure, as well as low-energy ion scattering techniques for surface characterization. He currently serves as the principal investigator for several Department of Energy (DOE) Office of Science programs at Sandia in Fusion Materials and Tritium Fuel Cycle R&D. In 2016, he received a five-year DOE Early Career Award to support his work on “Characterizing the Dynamic Response of Surfaces to High-Flux Plasma Exposure.”
Rob joined Sandia in 2006 as a postdoctoral researcher after earning his undergraduate degree in Mechanical Engineering from Rutgers University, followed by his M.S. and Ph.D. degrees from the California Institute of Technology.
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