Onset of fast magnetic reconnection via subcritical bifurcation

Abstract

Citation:Guo Z and Wang X (2015) Onset of fast magnetic reconnection via subcritical bifurcation. Front. Phys. 3:18. doi: 10.3389/fphy.2015.00018 Onset of fast magnetic reconnection via subcritical bifurcation 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 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, c ≃ √ 2 v the d e , where v the is π v c electron thermal velocity and v c is the velocity threshold of the st ream ing instability. For current driven ion acoustic, c is ≤ 10d e . If the thickness of the C S is narrower than c , the CS subcritically bifurcates into a rough state, which facilitates breakage of the CS, and consequently initiates fast reconnection.