Greifswald 2024 – scientific programme
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P: Fachverband Plasmaphysik
P 13: Magnetic Confinement IV/HEPP IV
P 13.3: Talk
Wednesday, February 28, 2024, 11:50–12:05, ELP 6: HS 3
The change of Jacobian of Poincaré map of magnetic island X/O-cycles under three-dimensional perturbation field — •Wenyin Wei1,2,3, Alexander Knieps1, and Yunfeng Liang1,2 — 1Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung - Plasmaphysik, Jülich 52425, Germany — 2Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, People’s Republic of China — 3University of Science and Technology of China, Hefei 230026, People’s Republic of China
Based on the first-order shift formula of X/O-cycles under perturbation, the change of Jacobian (denoted as DPm) of Poincaré map of X/O-cycles (of m toroidal turns) under perturbation is further investigated and formulated. Notably, neither the perturbation field nor the field to be perturbed is required to be axisymmetric or divergence-free for the formulae to apply.
In divertor configurations, the connection lengths of magnetic field lines in the scrape-off layer (SOL) are significantly affected by the DPm eigenvalues of the outmost X-cycle(s). The number of the outmost X-cycle(s) depends on the experiment setup. Tuning the eigenvalues of DPm of the X-cycle(s) closer to unity can markedly increase the connection lengths in the SOL, as the neighboring field lines will be more parallel to the X-cycles(s). Additionally, the width of a magnetic island is largely determined by the included angle of the two eigenvectors of DPm of the adjacent X-cycle(s).
Keywords: three-dimensional magnetic topology; dynamical system; island divertor; magnetic field structure and control; Jacobian of Poincare map