Poloidal cross section of the magnetosphere in the quasi-steady state. Green curves show poloidal magnetic field lines, and background color shows plasma density. The clouds of plasma above the polar cap form in e ± discharges. The absence of plasma (dark zone) above the separatrix shows the return-current gaps in the unscreened state; it fills with plasma every ∼2R LC/c during discharge episodes. Magnetic reconnection forms a dynamic plasmoid chain in the equatorial current sheet.