Plasmoid Instability Mediated Turbulent Reconnection, Simulations and Observations
Abstract
Abstract It has been established that the Sweet-Parker current layer in high Lundquist number reconnection is unstable to the super-Alfvenic plasmoid instability. Past two-dimensional magnetohydrodynamic simulations have demonstrated that the plasmoid instability leads to a new regime where the Sweet-Parker current layer changes into a chain of plasmoids connected by secondary current sheets, and the averaged reconnection rate becomes nearly independent of the Lundquist number. In this work we present results from recent three-dimensional simulations in which the additional degree of freedom allows development of plasmoid instabilities at oblique angles, which interact and lead to self-generated turbulent reconnection. This turbulent state exhibits typical hallmarks of MHD turbulence, such as power-law spectra of both kinetic and magnetic energy fluctuations, as well as eddies elongated along the local magnetic field direction. The averaged reconnection rate is of the order of a hundredth of the characteristic Alfven speed, which is similar to the two-dimensional result. Because plasmoid instability mediated reconnection has very different density and velocity structures from classic Sweet-Parker and Petschek models, it is possible to distinguish between them by high-resolution line-profiles observations. Comparing the Si iv line profiles obtained by the IRIS spectrometer observations of transition region explosive events with synthetic line profiles from simulations suggests that plasmoid instability mediated reconnection is in better agreement with observations.
- Publication:
-
Solar Heliospheric and INterplanetary Environment (SHINE 2015)
- Pub Date:
- July 2015
- Bibcode:
- 2015shin.confE..26H