2021/01/11 by Yuhang Luo, Yuhang, Luo, Zhe, Gao
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #FOS: Physical sciences #Geomagnetism and Paleomagnetism Studies #Ionosphere and magnetosphere dynamics #Plasma Physics (physics.plasm-ph) #Solar and Space Plasma Dynamics
paper · pdf · doi:10.48550/arxiv.2101.03750
openalex publication_date 2021/01/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The nonlinear dynamo effect of tearing modes is derived with the resistive MHD equations. The dynamo effect is divided into two parts, parallel and perpendicular to the magnetic field. Firstly, the force-free plasma is considered. It is found that the parallel dynamo effect drives opposite current densities at the different sides of the rational surface, making the λ=\boldsymbolj⋅\boldsymbolB/|\boldsymbolB|2 profile completely flattened near the rational surface. There are many rational surfaces for the turbulent plasma, which means the plasma is tending to relax into the Taylor state. In contrast, a bit far from the rational surface, the parallel dynamo effect is much smaller, and the nonlinear dynamo form approximates the quasilinear form. Secondly, the pressure gradient is included. It is found that rather than the λ profile, the \boldsymbolj⋅\boldsymbolB profile is flattened by the parallel dynamo effect. Besides, the perpendicular dynamo effect of tearing modes is found to eliminate the pressure gradient near the rational surface. In addition, our result also provides another basis for the assumption that current density is flat in the magnetic island for the tearing modes theory.