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There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
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You are invited to hear
give a talk entitled
Wednesday, August 24th from 3:00-4:00pm
Montgomery Knight 317
Advances in electrode, chamber, and structural materials will enable breakthroughs in future generations of electric propulsion and pulsed power (EP & PP) technologies. Although wide ranges of electric propulsion and pulsed power technologies have witnessed rapid advances during the past few decades, much of the progress was based on empirical development of materials through experimentation and trial-and-error approaches. To enable future technologies and to furnish the foundations for quantum leaps in performance metrics of these systems, a science-based materials development effort is required. We aim to develop new plasma-resilient material architectures that will enable future generations of electric propulsion and pulsed power technologies through an integrated research approach that combines multiscale modeling of plasma-material interactions, experimental validation, and material characterization. The range of materials of interest in EP & PP include refractory metals, such as tungsten and its alloys (W-Re) and molybdenum, ceramic composites, such as BN and Al2O3, high-strength copper alloys, and carbon-carbon composites. These classes of materials serve various design functions; primarily in cathode and anode applications, in accelerator grids, and in beam dumps of HPM sources. The presentation will give a review of our fundamental understanding for the limits of using these materials in EE & PP, and the opportunity to design material architectures that may dramatically improve their performance. We discuss the results of recent research related to three questions: (1) how can we control the thermomechanical response of materials in extreme heat flux and mitigate failure? (2) what are the phenomena that determine the unstable erosion of material surfaces in a plasma & ion environments?, and (3) How can we design materials that beneficially influence the plasma through Secondary Electron Emission (SEE) ? We first review the status of our experimental facilities for simulation of the space environment. Then, we present results of our understanding of the thermomechanics of materials in severe pulsed plasma environments, and the factors that control the erosive instabilities of surfaces. Finally, results of the effects of surface architectures on secondary electron emission will be given.
Professor Ghoniem holds the “Distinguished Professor” title of the University of California. He is currently professor of Mechanical and Aerospace Engineering, and is also of Materials Science & Engineering at UCLA. He has wide experience in the development of materials in severe environments (Nuclear, Mechanical and Aerospace). He developed some of main multiscale computational methods in defect physics and mechanics. He is a fellow of the American Nuclear Society, the American Academy of Mechanics, the American Society of Mechanical Engineers, the Japan Society for Promotion of Science, and The Materials Research Society. He was the general chair of the Second International Multiscale Materials Modeling Conference in 2004. He serves on the editorial boards of several journals, and has published over 350 articles, 10 edited books, and is the co-author of a two-volume book (Oxford Press) on the mechanics and physics of defects, computational materials science, radiation interaction with materials, instabilities and self-organization in non-equilibrium materials (Nasr Ghoniem and Daniel Walgraef, “Instabilities and Self-Organization in Materials: Part I-Fundamentals of Nanoscience, and Part II-Applications in Materials Design and Nanotechnology,”Oxford Press, 2007, 1100 pages.) He graduated 35 Ph.D. students and 25 post-doctoral scholars (14 are currently in faculty positions).
