Characteristics of a current sheet shear mode in collisionless magnetic reconnection

10th International Conference on Numerical Modeling of Space Plasma Flows: ASTRONUM-2015

Fujimoto, Keizo^1

Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Ohsawa, Mitaka, Tokyo

181-8588, Japan^1

关键词: Collisionless;    Current layers;    Current sheets;    Drift velocities;    Electromagnetic modes;    Electron dynamics;    Magnetic reconnections;    Velocity shear;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/719/1/012017/pdf
DOI  :  10.1088/1742-6596/719/1/012017

来源: IOP

【 摘 要 】

The current study shows the characteristics of the kink-type electromagnetic mode excited in the thin current layer formed around the x-line during the quasi-steady phase of magnetic reconnection. The linear wave analyses are carried out for the realistic current sheet profile which differs significantly from the Harris current sheet. It is found that the peak growth rate is very sensitive to the current sheet width even though the relative drift velocity at the center of the current sheet is fixed. This indicates that the mode is excited by the velocity shear rather than the relative drift velocity. Thus, the mode is termed here a current sheet shear mode. It is also shown that the wavenumber kyhas a clear mass ratio dependency as kyλi∝ (mi/me)1/4, implying the coupling of the ion and electron dynamics, where λiis the ion inertia length.