Triple splitting of a thin current sheet: A new type of plasma equilibrium

A hybrid numerical model of a one-dimensional current sheet in the Earth’s magnetotail is used to calculate a new self-consistent equilibrium state in the form of a triply split current sheet composed of three thin subsheets that are located close to each other and whose thickness is on the order of the ion gyroradius. The current in the central subsheet flows in the negative direction, opposite to the direction of the currents in the side subsheets. The magnetic field of the triply split current sheet has three neutral planes, in contrast to that of a classical bell-shaped current sheet with a single neutral plane at the sheet center. The particle dynamics in a triply split current configuration is analyzed. It is shown that, within the sheet, the current carriers—untrapped ions—move along meandering trajectories and can maintain an equilibrium structure self-consistently. It is found that a triply split current sheet is stable against external perturbations. The results obtained can help to explain complex dynamic processes occurring in the Earth’s magnetotail.