Presentation #126.06 in the session Explosive Energy Release Processes in the Solar Corona and Earth’s Magnetosphere — Poster Session.
Phenomena ranging from quiescent heating to explosive acceleration of plasma and particles are conjectured to result from magnetic reconnection onset at null-point current sheets in the solar corona and terrestrial magnetosphere. We employ ARMS, our magnetohydrodynamic (MHD) model with adaptive mesh refinement, to examine the self-consistent formation and reconnection of a current sheet in an initially potential, two-dimensional X-line configuration. Unequal stresses applied in the four quadrants bounded by the X-line separatrix quickly deform the null point into a double-Y-line current sheet, even in the high-beta region near the null. For a small but finite uniform resistivity, the macroscopically well-resolved current sheet lengthens until reconnection spontaneously sets in, accompanied by copious production, merging, and ejection of plasmoids. Similar behavior is seen routinely in global MHD simulations in which minimal numerical resistivity forms the current sheet as a grid-scale discontinuity. The roles of the slow linear phase of tearing and/or plasmoid instability, and of the structure and dynamics within the unresolved inner tearing layer, in such systems remain unclear, however. In order to investigate these issues, we extended our study to very slowly driven and highly resolved configurations. We discuss the implications of our results for understanding reconnection onset in the corona and magnetosphere and for gauging the robustness of global-scale MHD simulations of such processes.
Our research was supported by NASA’s H-ISFM and H-LWS programs.