Engineering Magnetic Fields with Scalar-Programmable Manifolds

Abstract
Theory and optimization have produced many candidate stellarator configurations, yet experimental validation remains limited and no clear consensus exists on the optimal design. This motivates coil concepts that support compact, flexible, lower-cost devices that explore multiple magnetic configurations and accelerate feedback between theory, optimization, and experiment.

A surface-functional framework is presented that approaches stellarator coil design using a programmable electromagnetic surface wrapping the plasma boundary. Its central object is a scalar function on this surface that determines how currents or fields are generated. While conventional coils are encompassed as one realization, the approach enables flexible interpretations due to the mathematical nature of the scalar, which. As electrical conductivity, it controls current distribution over the surface. This conductivity may be continuous or binary, realized through thickness variation, porosity, or patterned materials that guide prescribed paths. As electric potential, it defines voltage distributions driving surface currents; localized structures correspond to sources and sinks, batteries, capacitors, or electric dipoles. As magnetic permeability, it controls induced magnetization and offers passive shaping. These are realizations of the same surface-functional principle.

This perspective expands the stellarator design space through programmable surfaces. By exploiting non-unique inverse magnetostatic solutions, surface functionals can reproduce target fields while incorporating engineering constraints and reconfigurability.

Bio
Francisco Sáenz is a Ph.D. candidate in Mechanical and Aerospace Engineering at Princeton University and a graduate researcher at the Princeton Plasma Physics Laboratory (PPPL), where he works under the supervision of Professor Egemen Kolemen. His research focuses on advanced magnetic confinement concepts for nuclear fusion, including innovative stellarator design methods, liquid-metal plasma-facing components, and magnetohydrodynamics (MHD). His work combines theory, numerical modeling, optimization, and experiments to develop technologies that improve the performance and economic viability of future fusion power plants. He has developed computational tools for simulating electrically conductive fluid flows and electromagnetic systems under fusion-relevant conditions, while also contributing to the design and experimental validation of novel fusion concepts. His research has been published in journals including Nuclear Fusion and Physics of Plasmas and has contributed to patented technologies for advanced magnetic confinement devices.

Shear Dislocations in Supercooled Water

Abstract
Accurately modeling cloud and ice formation requires a deep understanding of processes that occur across multiple length scales, from atmospheric aerosols to molecular-scale water dynamics. Water droplets and ice-forming particles in the atmosphere play an important role in cloud formation, which affects how much sunlight is reflected or trapped by the Earth. However, the microscopic mechanisms that control how supercooled water relaxes remain poorly understood. In this work, we use molecular dynamics simulations to study how supercooled water rearranges at the molecular scale. By removing thermal fluctuations from these states, we identify localized rearrangements and measure the strain fields they generate in the surrounding liquid. We find that these rearrangements resemble dislocations in solids—localized “defects” appear to drive relaxation while producing long-ranged elastic-like responses. These results suggest that concepts from solid mechanics can help connect molecular-scale water dynamics to larger-scale environmental processes such as cloud and ice formation.

Bio
Debbie Zhuang completed her doctoral studies at MIT in chemical engineering under Martin Z. Bazant, focusing on degradation of lithium-ion batteries using mathematical modeling and theoretical approaches. Her work elucidated the importance of statistical effects in lithium-ion batteries, and helped bridge the gap between microscopic and macroscopic scales to improve the performance and lifetime of lithium-ion batteries. Following this, she worked in R&D at Samsung Semiconductor, aiding materials development from ab-initio to continuum methods for solid state batteries and semiconductor materials. Currently, as an Andlinger Distinguished Postdoctoral Fellow, she studies supercooled water and carbon dioxide for environmental applications using theoretical and computational approaches under the mentorship of Dimitrios Fraggedakis and Mike A. Webb. Her work will be used to understand and mitigate the environmental impacts of excess carbon dioxide in climate change.