Preprint
Effect of Controlled Magnetic Island Bifurcation on Electron Diffusion
ArXiv.org
Cornell University
01/27/2026
DOI: 10.48550/arxiv.2601.19073
Abstract
Magnetic islands strongly influence cross-field electron transport in magnetized plasmas. In particular, bifurcations of the island topology modify the number and location of O-points, X-points, and separatrix boundaries, thereby altering diffusion pathways. In recent DIII-D experiments, external magnetic perturbations were used to rotate and periodically bifurcate the island on the q = 2 surface, causing a switchback between a q = 2/1-dominated structure and a narrower q = 4/2-dominated structure. To investigate how this topological change affects electron transport, we employ the field line tracing code TRIP3D with an implemented collisional operator. Thermal, tracer electrons launched from O-points, X-points, and outside separatrix boundaries reveal distinct diffusion regimes, including classical, subdiffusive, and superdiffusive behavior, depending on both the dominant island mode and launch location. These results suggest that island bifurcation can alter electron diffusion across rational surfaces, with direct implications for particle confinement. While the present work emphasizes diffusion as a general framework, the findings provide insight into the conditions under which electron trapping into an island or stochastization of the island's separatrix can enable additional mechanisms, such as the generation of energetic electrons.
Details
- Title: Subtitle
- Effect of Controlled Magnetic Island Bifurcation on Electron Diffusion
- Creators
- Jessica EskewD. M OrlovB AndrewE BurschM KoepkeF SkiffM. E AustinT CoteC MariniE. G Kostadinova
- Resource Type
- Preprint
- Publication Details
- ArXiv.org
- DOI
- 10.48550/arxiv.2601.19073
- ISSN
- 2331-8422
- Publisher
- Cornell University; Ithaca, New York
- Language
- English
- Date posted
- 01/27/2026
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9985132081802771
Metrics
1 Record Views