Speaker: Dr. Adam McLean, Lawrence Livermore National Laboratory
Title: Diagnosing and Understanding the Tokamak Divertor
Abstract:
The divertor is an essential operational component for any current and future fusion tokamak, drawing away power and particles where they can transport, radiate and dissipate, then, ideally, be absorbed or pumped away in a way that is benign to the fusion core. To handle such fluxes even in current devices with mechanical and material limitations, transients and off-normal events, is arguably the principal challenge for fusion in the path to a future power plant where small size and high field are desirable, and the most critical design aspect to qualify, model, predict, and demonstrate at reactor-relevant conditions. This talk will cover the motivation for a divertor, the crucial role of radiation, material considerations on the plasma-facing wall, and transport and drifts physics occurring in the divertor. It will then dive into recent results and physics insight from a variety of diagnostics employed to measure parameters throughout the divertor and scrape-off layer (SOL) region whose output is key to validation of boundary modeling and the indispensable input for AI/ML/NN-based digital twin efforts. Future challenges and limitations for diagnostics in a reactor environment will be discussed, and finally, a perspective presented on the strengths of the collaborative model for fusion being pursued globally.
Bio: Born in the Canadian city of Barrie, Ontario, Dr. Adam McLean was lucky to know from a young age he wanted to pursue fusion research. While in 9th grade, he sent a letter to Prof. Peter Stangeby at the University of Toronto to ask how to do it; the reply he received set him on the path that led to his career today. After a long but valuable nine years as a PhD student at Toronto with experimental work at DIII-D, Adam accepted a postdoc with Oak Ridge at the Princeton Plasma Physics Lab. Under Dr. Rajesh Maingi, Adam developed infrared and probe-based first wall diagnostics. After that, he accepted a staff scientist position with Lawrence Livermore National Lab with Dr. Steve Allen’s group at DIII-D where he worked on Thomson scattering and EUV through NIR spectroscopy in the divertor and core, led experiments on detachment and drifts, and remained for 10 years. At the height of Covid, Adam and his family moved from DIII-D/San Diego back to PPPL/New Jersey to be closer to family in Canada and increasingly focus on bringing NSTX-U back to operations. Thanks to the magic of remote participation, however, he remained a strong participant in the DIII-D program. Dr. McLean currently splits his time between leading the Divertor & Scrape-Off Layer Science topical area at DIII-D, diagnostic development for SPARC, supporting diagnostics for NSTX-U restart, and operations at LTX-b and MAST-U. Adam is a US member of the Divertor and SOL group for the International Tokamak Physics Activity. He is married with two kids, and has happily embraced rural life in central NJ.
Seminar Access: In-person seminars are only available to CU ID holders. At this time, Non-Columbia affiliates and the general public are only invited to participate remotely. Contact [email protected] if you would like the Zoom link for this seminar.