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arXiv · 2609.27164

Effects of the Internal Transport Barrier in the plasma confinement with Resonant Magnetic Perturbations

P. Haerter·L. C. Souza·R. L. Viana·I. L. Caldas
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Abstract

In the pursuit of steady-state fusion energy, Advanced Tokamak regimes rely on Internal Transport Barriers (ITBs) with reversed magnetic shear. While Resonant Magnetic Perturbations (RMPs) are commonly applied to control Edge Localized Modes (ELMs) by intentionally making the plasma edge chaotic, the RMPs can also affect the reversed-shear cores. To address this compatibility, we propose a new, adjustable analytical model for plasma current that explicitly incorporates the core, ITB, and edge pedestal components. By applying this current formulation to a Hamiltonian map, we compare how easily magnetic chaos reaches the core in ITB-driven reversed-shear (Non-Twist) plasmas. We find that the localized ITB current creates "twin" inner resonances and pushes outer magnetic island chains closer to the edge. These results highlight a critical operational trade-off: while the Non-Twist topology makes ELM control easier at lower coil currents, it severely shrinks the safety margin against a complete, RMP-induced loss of global confinement.

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P. Haerter, L. C. Souza, R. L. Viana, I. L. Caldas. 2026-09-22. Effects of the Internal Transport Barrier in the plasma confinement with Resonant Magnetic Perturbations. https://arxiv.org/abs/2609.27164

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