May 10, 2026

Paper on Controlled Magnetic Island Bifurcation and Electron Diffusion Published in Nuclear Fusion

Our paper, “Effect of Controlled Magnetic Island Bifurcation on Electron Diffusion,” has been published in Nuclear Fusion. The work was carried out by Jessica Eskew and Eva G. Kostadinova (Auburn University), Dmitri M. Orlov and C. Marini (University of California San Diego), E. Bursch (Columbia University), M. Koepke (West Virginia University), F. Skiff (University of Iowa), M. E. Austin (The University of Texas at Austin), and T. Cote (General Atomics).

The study investigates how controlled changes in magnetic island topology affect electron diffusion and transport in magnetized plasmas. Using DIII-D Frontiers Science experiments together with TRIP3D field-line tracing simulations incorporating a collisional operator, the work analyzes transitions between q=2/1 and bifurcated q=4/2 magnetic island structures produced by externally applied magnetic perturbations. The simulations demonstrate that electron transport strongly depends on both the island topology and the particle launch location relative to O-points and X-points, resulting in subdiffusive, classical, and superdiffusive transport regimes. The experiments also revealed periodic bursts of hard X-ray emission synchronized with the island bifurcation, suggesting enhanced energetic electron deconfinement during transitions to the narrower q=4/2 structure. These results improve understanding of transport and confinement in stochastic magnetic topologies and may help inform future studies of energetic electron dynamics in fusion plasmas.

The publication is available online at: https://doi.org/10.1088/1741-4326/ae6ab3