Plasmoid-dominated turbulent reconnection in symmetric and asymmetric systems

<p>In magnetohydrodynamics (MHD), magnetic reconnection has been discussed by three theoretical models: Sweet--Parker reconnection, Petschek reconnection, and plasmoid-dominated turbulent reconnection. Among these models, properties of plasmoid-dominated reconnection remain unclear, because it was discovered only recently.&#160;In this talk, we explore basic properties of plasmoid-dominated reconnection in a low-beta plasma such as in a solar corona, by using large-scale MHD simulations [1]. We have found that the system becomes highly complex due to repeated formation of plasmoids and shocks. We have further found that the reconnection rate goes higher than previously thought.&#160;Next we explore influence of asymmetry in background plasma densities in plasmoid-dominated reconnection. We have found that the average reconnection rate follows Cassak-Shay's hybrid relation [2]. Many signatures become asymmetric across the reconnection layer, and plasmas inside the plasmoids start to swirl in specific directions. Formation processes of these vortices and a potential extension of our numerical survey will be discussed.<br><br>References:<br>[1] S. Zenitani and T. Miyoshi, <em>Astrophys. J. Lett.</em>, 894, L7 (2020)<br>[2] P. A. Cassak and M. A. Shay, <em>Phys. Plasmas,</em> 14, 102114 (2007)<br><br></p>