Onset of fast magnetic reconnection via subcritical bifurcation

Frontiers in Physics

Guo, Zhibin¹  Wang, Xiaogang² 

[1] State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing, China;WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon, South Korea

关键词: Magnetic Reconnections;    fast reconnection;    Current sheets;    bifurcation analysis;    Plasma waves;   

DOI  :  10.3389/fphy.2015.00018

学科分类：物理（综合）

来源: Frontiers

【 摘 要 】

We report a phase transition model for the onset of fast magnetic reconnection. By investigating the joint dynamics of streaming instability(i.e., current driven ion acoustic in this paper) and current gradient driven whistler wave {\color{blue} {prior to the onset of fast reconnection}}, we show that the nonlinear evolution of current sheet(CS) can be described by a Landau-Ginzburg equation. The phase transition from slow reconnection to fast reconnection occurs at a critical thickness, $\Delta_c\simeq \frac{2}{\sqrt{\pi}}\left|\frac{v_{the}}{v_c}\right|d_e$, where $v_{the}$ is electron thermal velocity and $v_c$ is the velocity threshold of the streaming instability. For current driven ion acoustic, $\Delta_c$ is $\leq10d_e$. If the thickness of the CS is narrower than $\Delta_c$, the CS subcritically bifurcates into a rough state, which facilitates breakage of the CS, and consequently initiates fast reconnection.

【 授权许可】

CC BY