Explosive Turbulent Magnetic Reconnection

We report simulation results for turbulent magnetic reconnection obtained using a newly developed Reynolds-averaged magnetohydrodynamics model. We find that the initial Harris current sheet develops in three ways, depending on the strength of turbulence: laminar reconnection, turbulent reconnection, and turbulent diffusion. The turbulent reconnection explosively converts the magnetic field energy into both kinetic and thermal energy of plasmas, and generates open fast reconnection jets. This fast turbulent reconnection is achieved by the localization of turbulent diffusion. Additionally, localized structure forms through the interaction of the mean field and turbulence.

Figure 1

Time evolution of the reconnected magnetic fluxes in the cases of $C_{\tau }=0.05$ (black), $C_{\tau }=0.5$ (blue), $C_{\tau }=1.2$ (red), and $C_{\tau }=3.0$ (dark green). In Run $C’$ (red-dashed), $\mathcal{W}$ is forced to be 0 throughout the calculation.

Figure 2

Reconnected magnetic fluxes at $t/{\tau }_A=254$ vs $C_{\tau }$. Red points stand for simulation runs with different $C_{\tau }$ values.

Figure 3

$y$ components of the electric currents in the laminar ($C_{\tau }=0.05$) and turbulent ($C_{\tau }=1.2$, 3.0) cases at $t/{\tau }_A=254$ are shown as color contour plots. Black arrows show the flow velocity.

Figure 4

The upper two contour plots show the spatial distributions of the turbulent energy $\mathcal{K}$ and the cross helicity $\mathcal{W}$ near the magnetic neutral point in the case of $C_{\tau }=1.2$. The bottom panel shows the spatial distribution of $\mathcal{K}$ at $C_{\tau }=1.2$, where $\mathcal{W}$ is switched off throughout the calculation. These three snapshots are taken at time $t/{\tau }_A=254$.