Work

Two-fluid effects on the nonlinear dynamics of RFP relaxation

Year: 2026

Type: preprint

Abstract: This study investigates the role of two-fluid effects during magnetic relaxation in reversed-field pinch (RFP) plasmas. Within the multiple-helicity (MH) regime, two-fluid simulations produce distinct sawtooth oscillations, in contrast to the sawtooth-free state obtained in single-fluid simulations. Analysis of the magnetic field aligned projection of Faraday's law reveals that, tearing modes collectively generate a dynamo electric field that sustains the magnetic relaxation, a process analogous to the flux-pumping in tokamaks. Despite the reduced linear tearing-mode growth rates, stronger two-fluid effects produce more pronounced sawtooth activity over the parameter range considered. Modal energy analysis shows that Hall-mediated nonlinear energy redistribution disrupts the coherent tearing-mode dynamics required to sustain steady flux-pumping, thereby facilitating intermittent reconnection. This transition is interpreted as a Hall-mediated dynamical bifurcation between steady flux-pumping and quasi-periodic sawtooth relaxation.

Source: arXiv (Cornell University)

DOI: 10.48550/arxiv.2608.20774

Authors: Yan, Wentan, Zhu, Ping, Li, Hong, Liu, Wandong, Luo, Bing

Institutions: University of Science and Technology of China, University of Wisconsin–Madison, State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Hunan University of Arts and Science

Topic: Magnetic confinement fusion research

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: green

Funders: U.S. Department of Energy, National Natural Science Foundation of China, University of Science and Technology of China

Awards: G222768804, FUSION PLASMA THEORY, G4753533600

OpenAlex ID: W7204127405

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