This talk will introduce how modern optimization techniques and computational tools are used to design stellarators—3D, current-free fusion devices whose performance depends critically on carefully tailored geometry—and will outline key methods, challenges, and open research questions shaping their future.
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Stellarators are sometimes described as the “twisted cousin” of tokamaks because, unlike tokamaks, they are not limited to (approximately) axisymmetric equilibria and instead allow for fully three-dimensional (3D) shaping. This expanded design space offers a key advantage: the ability to generate rotational transform without relying on a net plasma current. As a result, stellarators can achieve steady-state operation and exhibit enhanced stability against current-driven instabilities.
However, these benefits do not automatically follow from any arbitrary 3D shape. Poorly optimized configurations can lead to degraded confinement and increased instabilities. To unlock the full potential of stellarators, their geometry must be carefully tailored through optimization.
This presentation provides an overview of stellarator optimization methods and the computational tools that enable them. Topics include equilibrium codes, plasma boundary, coil and divertor optimization approaches and tools. We will also highlight open questions and active research areas that shape the future of stellarator design.
Dr. Sophia Henneberg is an Assistant Professor at MIT whose research focuses on developing, utilizing, and extending optimization tools to discover new, advantageous stellarator designs, a promising path toward achieving fusion energy. Among her research contributions, she led the invention of a novel stellarator–tokamak hybrid concept (featured in Physical Review Research and covered by New Scientist), and she pioneered methods for “single-stage” optimization that simultaneously considers plasma and coil design, a crucial step toward feasible stellarator configurations.
Dr. Henneberg has played a leading role in several international collaborations. She served as Principal Investigator of the Stellarator Optimization TSVV (Theory, Simulation, Validation, and Verification) group, a European consortium including institutes in Spain, Switzerland, Finland, and Germany. She was a core member of the Simons Collaboration on “Hidden Symmetries and Fusion Energy,” which advanced stellarator optimization research globally. Previously, she was the Stellarator Optimization Task Leader for HILOADS (Helmholtz International Laboratory for Optimized Advanced Divertor in Stellarators), a U.S.–German collaboration.
Her academic journey began with a bachelor’s degree from Goethe University Frankfurt, followed by a Fulbright year earning a master’s degree in Madison, Wisconsin. She completed her Ph.D. at the University of York in 2016 under the supervision of Prof. Howard Wilson and in close collaboration with Prof. Sir Steve Cowley. Her doctoral research focused on modeling Edge Localized Modes (ELMs) using the nonlinear ballooning mode envelope equation derived from ideal MHD theory, describing the filamentary and explosive behavior of ELMs.
